Resin composition, resin sheet, multilayer printed wiring board, and semiconductor device

ABSTRACT

Provided is a resin composition which has good solubility and photocurability, further has good alkaline-developability when containing a photo initiator and a compound containing one or more carboxyl groups, and in addition, is capable of providing a resin sheet having suppressed tackiness; and a resin sheet, multilayer printed wiring board, and semiconductor device using the same. The resin composition of the present invention contains a particular bismaleimide compound (A), and at least two maleimide compounds (B) selected from the group consisting of six kinds of particular compounds which are different from this bismaleimide compound (A).

TECHNICAL FIELD

The present invention relates to a resin composition, and a resin sheet, multilayer printed wiring board, and semiconductor device using the same.

BACKGROUND ART

Due to the downsizing and densification of multilayer printed wiring boards, studies to make the laminate used for multilayer printed wiring boards thinner have been actively carried out. Along with the thinning, the insulation layer also needs to be made thinner, and a resin sheet not containing glass cloth has been demanded. The resin composition used as the material of the insulation layer is mainly a thermosetting resin, and drilling of holes between insulation layers to obtain conduction is generally carried out by laser processing.

Meanwhile, the drilling of holes by laser processing has a problem that the processing time becomes longer as the number of holes in a high density substrate becomes larger. In recent years, therefore, there has been a demand for a resin sheet that enables batch drilling in the exposure and development steps by using a resin composition in which an exposed portion is cured by irradiation of rays of light or the like (exposure step) and an unexposed portion can be removed (development step).

As the method of exposure, a method in which a mercury lamp is used as a light source and the exposure is carried out via a photomask is used. A material which can be suitably exposed in the method using a mercury lamp as a light source has been demanded. In the exposure method using a mercury lamp as a light source, a ghi-line (a g-line with a wavelength of 436 nm, an h-line with a wavelength of 405 nm and an i-line with a wavelength of 365 nm) or the like is used, and a general-purpose photo initiator can be selected. Also, in recent years, the introduction of a direct imaging method, in which a pattern is directly drawn on the photosensitive resin composition layer without using a photomask, based on digital data of the pattern, has also been progressing as the exposure method. Since this direct imaging method provides better alignment accuracy than the exposure method using a photomask and produces a more detailed pattern, the introduction of this method has been progressing, especially for substrates that require the formation of high density wiring. The light source for this method is a monochromatic light source such as a laser, and in particular, a light source with a wavelength of 405 nm (h-line) is used in devices based on the DMD (Digital Micromirror Device) system, which is capable of forming highly detailed resist patterns.

As a development method, alkaline development is employed because a highly detailed pattern can be obtained.

For the photosensitive resin compositions used in laminates and resin sheets, compounds having an ethylenically unsaturated group, such as (meth)acrylate, are used in order to enable rapid curing in the exposure step.

Patent Document 1 describes a resin composition containing a bismaleimide compound (a curable resin) and a photo radical polymerization initiator (a curing agent) as a photosensitive resin composition used for laminates and resin sheets.

Patent Document 2 describes a resin composition containing a curable resin such as an epoxy resin and a polyvalent carboxy group-containing compound obtained by reacting bismaleimide with a monoamine, and then reacting an acid anhydride. Patent Document 2 describes a polyvalent carboxy group-containing compound which enables production of a cured product having alkaline-developability.

CITATION LIST Patent Document

-   Patent Document 1: International Publication No. WO 2018/56466 (A1) -   Patent Document 2: Japanese Patent Laid-Open No. 2015-229734

SUMMARY OF INVENTION Technical Problem

However, cured products using conventional (meth)acrylate-based resins do not provide a sufficient physical property, and are limited in forming excellent protective films and interlayer insulation layers. In addition, these cured products do not have sufficient alkaline-developability, do not produce highly detailed resist patterns, and are problematic for use as high density printed wiring boards in an unexposed portion.

In Patent Document 1, a bismaleimide compound is used as a curable resin, but since the maleimide compound normally has poor light transmissivity, when the maleimide compound is contained, light does not reach the photo initiator sufficiently, the photo initiator has difficulty generating radicals, and its reactivity is very low. Therefore, in Patent Document 1, the maleimide compound is cured by additional heating before development, and highly detailed resist patterns cannot be obtained because heating is performed. Since originally, the resin composition described in Patent Document 1 does not have sufficient alkaline-developability, an unexposed resin composition remains even after development. This also suggests that in Patent Document 1, a highly detailed resist pattern cannot be obtained, and the resin composition cannot be used for production of high density printed wiring boards.

For obtaining the polyvalent carboxy group-containing compound described in Patent Document 2, it is necessary to react bismaleimide with a monoamine and then react an acid anhydride, so that the process is complicated. In addition, an aromatic amine compound is used as the monoamine, and therefore the polyvalent carboxy group-containing compound contains an amide group having an aromatic ring in the structure thereof. Thus, the polyvalent carboxy group-containing compound is poor in light transmissivity, hinders photocuring reaction, and is therefore difficult to use for photosensitive resin compositions in reality.

As a result of intensive studies, the present inventors have found that the resin composition containing maleimide compounds normally has poor compatibility between the maleimide compounds and other compounds and has therefore poor solubility in an organic solvent, and it is difficult to use such a resin composition for varnish.

Meanwhile, the present inventors have found that a varnish containing a maleimide compound and having excellent solubility contains liquid components in large amounts, and the resin sheet obtained therefrom has therefore strong tackiness even when dried.

The present invention has been made in view of the problems described above, and an object of the present invention is to provide a resin composition which has good solubility and photocurability, further has good alkaline-developability when containing a photo initiator and a compound containing one or more carboxyl groups, and in addition, is capable of providing a resin sheet having suppressed tackiness; and a resin sheet, multilayer printed wiring board, and semiconductor device using the same.

Solution to Problem

As a result of intensive studies, the present inventors have found that a resin composition containing a particular bismaleimide compound (A) and at least two maleimide compounds (B) selected from the group consisting of six kinds of particular compounds which are different from this bismaleimide compound (A) has good solubility and photocurability, and when further containing a photo initiator and a compound containing one or more carboxyl groups, the resin composition has excellent alkaline-developability while having good solubility and photocurability, and also found that a resin sheet obtained from the resin composition has satisfactorily suppressed tackiness, while having photocurability and alkaline-developability, leading to completion of the present invention.

More specifically, the present invention includes the following contents.

[1] A resin composition containing a bismaleimide compound (A) containing a constituent unit represented by the following formula (1) and maleimide groups at both ends of the molecular chain, and at least two maleimide compounds (B) selected from the group consisting of a compound represented by the following formula (2), a compound represented by the following formula (3), a compound represented by the following formula (4), a compound represented by the following formula (5), a compound represented by the following formula (6), and a compound represented by the following formula (7):

wherein R₁ represents a linear or branched alkylene group having 1 to 16 carbon atoms, or a linear or branched alkenylene group having 2 to 16 carbon atoms; R₂ represents a linear or branched alkylene group having 1 to 16 carbon atoms, or a linear or branched alkenylene group having 2 to 16 carbon atoms; each R₃ independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 16 carbon atoms, or a linear or branched alkenyl group having 2 to 16 carbon atoms; and each n₁ independently represents an integer of 1 to 10,

wherein each of R₄, R₅, and R₆ independently represents a hydrogen atom, a hydroxyl group, or a linear or branched alkyl group having 1 to 6 carbon atoms and optionally having a substituent; and n₂ represents an integer of 1 to 10,

wherein each R₇ independently represents a hydrogen atom or a methyl group; and n₃ represents an integer of 1 to 10,

wherein each of R₈, R₉, and R₁₀ independently represents a hydrogen atom, or a linear or branched alkyl group having 1 to 8 carbon atoms and optionally having a substituent,

wherein each R₁₁ independently represents a hydrogen atom, a methyl group, or an ethyl group; and each R₁₂ independently represents a hydrogen atom or a methyl group,

wherein each R₁₃ independently represents a hydrogen atom, a methyl group, or an ethyl group, and

wherein each R₁₄ independently represents a hydrogen atom or a methyl group; and n₄ represents an integer of 1 to 10.

[2] The resin composition according to [1], further containing a photo initiator (C).

[3] The resin composition according to [2], wherein the photo initiator (C) contains a compound represented by the following formula (8):

wherein each R₁₅ independently represents a group represented by the following formula (9) or a phenyl group; and

wherein —* represents a bonding hand, and each R₁₆ independently represents a hydrogen atom or a methyl group.

[4] The resin composition according to any of [1] to [3], further containing a compound (D) containing one or more carboxy groups.

[5] The resin composition according to [4], wherein the compound (D) containing one or more carboxy groups is at least one selected from the group consisting of a compound represented by the following formula (10), a compound represented by the following formula (11), a compound represented by the following formula (12), and a compound represented by the following formula (13):

wherein each R₁₇ independently represents a hydrogen atom, a hydroxyl group, a carboxy group, an amino group or an aminomethyl group; each k independently represents an integer of 1 to 5; and when two or more carboxy groups are present, the carboxy groups are optionally linked together to form an acid anhydride,

wherein each R₁₈ independently represents a hydrogen atom, a hydroxyl group, a carboxy group, a carboxymethyl group, an amino group or an aminomethyl group; each 1 independently represents an integer of 1 to 9; when two or more carboxy groups are present, the carboxy groups are optionally linked together to form an acid anhydride; and when a carboxymethyl group is present, the carboxymethyl group and the carboxy group are optionally linked together to form an acid anhydride,

wherein each R₁₉ independently represents a hydrogen atom, a hydroxyl group, a carboxy group, a carboxymethyl group, an amino group or an aminomethyl group; each m independently represents an integer of 1 to 9; when two or more carboxy groups are present, the carboxy groups are optionally linked together to form an acid anhydride; and when a carboxymethyl group is present, the carboxymethyl group and the carboxy group are optionally linked together to form an acid anhydride, and

wherein each R₂₀ independently represents a hydrogen atom, a hydroxyl group, a carboxy group, a carboxymethyl group, an amino group or an aminomethyl group; each o independently represents an integer of 1 to 5; when one or more carboxy groups are present, the carboxymethyl group and the carboxy group are optionally linked together to form an acid anhydride; when two or more carboxy groups are present, the carboxy groups are optionally linked together to form an acid anhydride; and when two or more carboxymethyl groups are present, the carboxymethyl groups are optionally linked together to form an acid anhydride.

[6] A resin sheet containing a support; and a resin layer disposed on one surface or both surfaces of the support, wherein the resin layer contains the resin composition according to any of [1] to [5].

[7] The resin sheet according to [6], wherein the resin layer has a thickness of 1 to 50 μm.

[8] A multilayer printed wiring board containing an insulation layer; and a conductor layer formed on one surface or both surfaces of the insulation layer, wherein the conductor layer contains the resin composition according to any of [1] to [5].

[9] A semiconductor device containing the resin composition according to any of [1] to [5].

Advantageous Effects of Invention

The present invention can provide a resin composition which has good solubility and photocurability, further has good alkaline-developability when containing a photo initiator and a compound containing one or more carboxyl groups, and in addition, is capable of providing a resin sheet having suppressed tackiness; and a resin sheet, multilayer printed wiring board, and semiconductor device using the same.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 shows a ¹H-NMR chart of an amide acid compound (MA-TMDA).

FIG. 2 shows a ¹H-NMR chart of a maleimide compound (TMDM).

FIG. 3 shows photographs after alkaline development performed with the use of resin sheets obtained using an activity energy ray including a wavelength of 405 nm (h-line) in Example 1 and Comparative Example 6.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment for carrying out the present invention (hereinafter, referred to as the “present embodiment”) will be described in detail. The present embodiment described below is only illustrative of the present invention and is not intended to limit the present invention to the contents of the following description. The present invention can be carried out with appropriate modifications falling within the gist of the invention.

Note that, in the present specification, the term “(meth)acryloxy” refers to both “acryloxy” and “methacryloxy” corresponding thereto, the term “(meth)acrylate” refers to both “acrylate” and “methacrylate” corresponding thereto, and the term “(meth)acryl” refers to both “acryl” and “methacryl” corresponding thereto.

[Resin Composition]

The resin composition of the present embodiment contains a particular bismaleimide compound (A), and at least two maleimide compounds (B) selected from the group consisting of a compound represented by the formula (2), a compound represented by the formula (3), a compound represented by the formula (4), a compound represented by the formula (5), a compound represented by the formula (6), and a compound represented by the formula (7). Hereinafter, each of these components will be described.

<Bismaleimide Compound (A)>

The resin composition contains a bismaleimide compound (A) (also referred to as component (A)). The bismaleimide compound (A) contains a constituent unit represented by the formula (1), and maleimide groups at both ends of the molecular chain.

In the formula (1), R₁ represents a linear or branched alkylene group having 1 to 16 carbon atoms, or a linear or branched alkenylene group having 2 to 16 carbon atoms. R₂ represents a linear or branched alkylene group having 1 to 16 carbon atoms, or a linear or branched alkenylene group having 2 to 16 carbon atoms. Each R₃ independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 16 carbon atoms, or a linear or branched alkenyl group having 2 to 16 carbon atoms. Each n₁ independently represents an integer of 1 to 10.

The present inventors estimate the reason why the resin composition has excellent photocuring reactivity by containing the maleimide compounds (B) together with the bismaleimide compound (A) is as follows.

Normally, since maleimide compounds have poor light transmissivity, when the resin composition contains a maleimide compound, light does not sufficiently reach the photo initiator dispersed in the resin composition, and the photo initiator has difficulty generating radicals. Therefore, in general, the photo radical reaction of maleimide compounds is difficult to proceed, and even if radical polymerization or dimerization reaction of single maleimide proceeds, its reactivity is very low. However, the bismaleimide compound (A) contains a constituent unit represented by the formula (1), that is, an alicyclic backbone, and therefore has superior light transmissivity. Therefore, light reaches the photo initiator sufficiently, so that the photo radical reaction of the maleimide efficiently takes place. Using various active energy rays, the bismaleimide compound (A) and the later-described maleimide compounds (B) can be photocured together with the later-described photo initiator (C) and the later-described compound (D) containing one or more carboxyl groups which are compounded if required.

The bismaleimide compound (A) exhibits superior light transmissivity, with a transmittance of 5% or more, when a chloroform solution containing the bismaleimide compound (A) at 1% by mass is prepared and the transmittance of the chloroform solution containing the bismaleimide compound (A) at 1% by mass is measured using an active energy ray including a wavelength of 365 nm (i-line). In addition, the bismaleimide compound (A) exhibits superior light transmissivity, with a transmittance of 5% or more, when the transmittance of the chloroform solution containing the bismaleimide compound (A) at 1% by mass is measured using an active energy ray including a wavelength of 405 nm (h-line). Therefore, for example, upon producing a printed wiring board having a highly dense and highly detailed wiring formation (pattern) using the direct imaging method, the photo radical reaction of the maleimide occurs efficiently even when an active energy ray including a wavelength of 405 nm (h-line) is used. The transmittance at a wavelength of 365 nm (i-line) is preferably 8% or more, more preferably 10% or more, from the viewpoint of exhibiting superior light transmissivity. The transmittance at a wavelength of 405 nm (h-line) is preferably 8% or more, more preferably 10% or more, from the viewpoint of producing a printed wiring board having a more highly dense and highly detailed wiring formation (pattern). The upper limit of each of the transmittance at a wavelength of 365 nm (i-line) and the transmittance at a wavelength of 405 nm (h-line) is, for example, 99.9% or less.

Normally, the absorbance of the photo initiator tends to decrease with respect to a light in a long wavelength region. For example, when an active energy ray (ray of light) including a wavelength of 405 nm (h-line) is used, a usual photo initiator does not absorb the ray because light having such a wavelength has a relatively long wavelength, and polymerization proceeds only when a photo initiator capable of suitably absorbing the light to generate radicals is used. Therefore, as the later-described photo initiator (C), a photo initiator is preferably used which exhibits superior absorption of light with a wavelength of 405 nm (h-line), with an absorbance of 0.1 or more, when the absorbance of a chloroform solution containing the photo initiator (C) at 0.01% by mass is measured.

Since the bismaleimide compound (A) has excellent light transmissivity as mentioned above, light reaches the photo initiator sufficiently, for example, even when an active energy ray including a wavelength of 365 nm or an active energy ray including a wavelength of 405 nm is used, radical reaction using radicals generated from the photo initiator proceeds, and even a composition containing a large amount of the bismaleimide compound (A) can be photocured.

In addition, the present inventors estimate the reason why the resin sheet obtained from the resin composition having good solubility has satisfactorily suppressed tackiness while having photocurability and alkaline-developability is as follows.

Normally, the resin composition containing maleimide compounds has poor compatibility between the maleimide compounds or between the maleimide compounds and a photo initiator or other compounds such as a compound containing one or more carboxy groups. Therefore, the resin composition has poor solubility in an organic solvent, and it is difficult to make such a resin composition into a varnish. Meanwhile, even if a varnish contains a maleimide compound and has excellent solubility, such a varnish contains liquid components in large amounts, and the resin sheet obtained therefrom has therefore a problem of strong tackiness even by drying the varnish. However, the resin composition obtained by mixing the bismaleimide compound (A) and at least two or more of the later-described specific maleimide compounds (B) has excellent compatibility while having excellent photocurability, resulting in good solubility in an organic solvent. In addition, when the resin composition is used for a varnish, the resin sheet obtained by drying the varnish has satisfactorily suppressed tackiness because the amount of liquid components in the varnish is small.

Furthermore, normally, maleimide compounds have extremely low water solubility, do not have reactivity with an alkaline component in an alkaline developing solution, and therefore hardly exhibit alkaline developability. However, in the present embodiment, the later-described photo initiator (C) and the later-described compound (D) containing one or more carboxyl groups are contained together with the bismaleimide compound (A) and the maleimide compounds (B), so that the resin composition having superior alkaline-developability while having excellent photocurability and solubility in an organic solvent is obtained. The reason for this is not certain, but the present inventors estimate it as follows. That is, the bismaleimide compound (A) has a relatively long chain and a flexible structure, and does not have a structure which causes interaction with an alkaline component in the alkaline developing solution. The maleimide compounds (B) and the initiator (C) do not also have a structure which causes interaction with an alkaline component in the alkaline developing solution. Therefore, these compounds (A), (B), and the initiator (C) can be dissolved in the alkaline developing solution as the compound (D) is dissolved in the alkaline developing solution while the structure of the compound (D) is maintained in the alkaline developing solution. When in a development step, the alkaline developing solution flows into an unexposed portion (resin composition), the alkaline component in the alkaline developing solution and a carboxy group in the compound (D) can quickly and suitably form a salt without being hindered by these compounds (A), (B), and the initiator (C), and water-solubility is thus improved. This may be the reason why the resin composition has excellent alkaline developability. Thus, the amount of liquid components is small also in the varnish obtained from this resin composition, and thus the tackiness of the resin sheet obtained by drying the varnish is satisfactorily suppressed.

Cured products obtained from the resin composition have excellent heat resistance, insulation reliability, and thermal stability. Therefore, according to the present embodiment, protective films and insulation layers in multilayer printed wiring boards and semiconductor devices can be suitably formed.

The mass average molecular weight of the bismaleimide compound (A) is not particularly limited as long as the effect of the present invention is achieved, and is preferably 100 to 5000, and more preferably 300 to 4500 because a suitable viscosity can be obtained and an increase in viscosity of varnish can be suppressed. In the present embodiment, the term “mass average molecular weight” means a mass average molecular weight in terms of polystyrene standard by a gel permeation chromatography (GPC) method.

The structure of the bismaleimide compound (A) will now be described.

In the formula (1) of the bismaleimide compound (A), R₁ represents a linear or branched alkylene group having 1 to 16 carbon atoms, or a linear or branched alkenylene group having 2 to 16 carbon atoms. R₁ is preferably a linear or branched alkylene group, and more preferably a linear alkylene group because a suitable viscosity can be obtained and an increase in viscosity of varnish can be controlled.

The number of carbon atoms in the alkylene group is preferably 2 to 14, and more preferably 4 to 12 because a more suitable viscosity can be obtained and an increase in viscosity of varnish can be more reliably controlled.

Examples of the linear or branched alkylene group include a methylene group, an ethylene group, a propylene group, a 2,2-dimethylpropylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, a dodecylene group, an undecylene group, a tridecylene group, a tetradecylene group, a pentadecylene group, a hexadecylene group, a neopentylene group, a dimethylbutylene group, a methylhexylene group, an ethylhexylene group, a dimethylhexylene group, a trimethylhexylene group, a methylheptylene group, a dimethylheptylene group, a trimethylheptylene group, a tetramethylheptylene group, an ethylheptylene group, a methyloctylene group, a methylnonylene group, a methyldecylene group, a methyldodecylene group, a methylundecylene group, a methyltridecylene group, a methyltetradecylene group and a methylpentadecylene group.

The number of carbon atoms in the alkenylene group is preferably 2 to 14, and more preferably 4 to 12 because a more suitable viscosity can be obtained and an increase in viscosity of varnish can be more reliably controlled.

Examples of the linear or branched alkenylene group include a vinylene group, a 1-methylvinylene group, an arylene group, a propenylene group, an isopropenylene group, a 1-butenylene group, a 2-butenylene group, a 1-pentenylene group, a 2-pentenylene group, an isopentylene group, a cyclopentenylene group, a cyclohexenylene group, and a dicyclopentadienylene group.

In the formula (1), R₂ represents a linear or branched alkylene group having 1 to 16 carbon atoms, or a linear or branched alkenylene group having 2 to 16 carbon atoms. R₂ is preferably a linear or branched alkylene group, and more preferably a linear alkylene group because a suitable viscosity can be obtained and an increase in viscosity of varnish can be controlled.

The number of carbon atoms in the alkylene group is preferably 2 to 14, and more preferably 4 to 12 because a more suitable viscosity can be obtained and an increase in viscosity of varnish can be more reliably controlled.

For the linear or branched alkylene group, R₁ can be referred to.

The number of carbon atoms in the alkenylene group is preferably 2 to 14, and more preferably 4 to 12 because a more suitable viscosity can be obtained and an increase in viscosity of varnish can be more reliably controlled.

For the linear or branched alkenylene group, R₁ can be referred to.

In the formula (1), R₁ and R₂ may be the same or different, and are preferably the same because the bismaleimide compound (A) can be more easily synthesized.

In the formula (1), each R₃ independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 16 carbon atoms, or a linear or branched alkenyl group having 2 to 16 carbon atoms. It is preferable that each R₃ be independently a hydrogen atom or a linear or branched alkyl group having 1 to 16 carbon atoms because a suitable viscosity can be obtained and an increase in viscosity of varnish can be controlled, it is more preferable that one to five groups (R₃s) among R₃s be linear or branched alkyl groups each having 1 to 16 carbon atoms, and other groups (R₃) be hydrogen atoms, and it is still more preferable that one to three groups (R₃s) among R₃s be linear or branched alkyl groups each having 1 to 16 carbon atoms, and other groups (R₃) be hydrogen atoms.

The number of carbon atoms in the alkyl group is preferably 2 to 14, and more preferably 4 to 12 because a more suitable viscosity can be obtained and an increase in viscosity of varnish can be more reliably controlled.

Examples of the linear or branched alkyl group include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a 1-ethylpropyl group, a n-butyl group, a 2-butyl group, an isobutyl group, a tert-butyl group, a n-pentyl group, a 2-pentyl group, a tert-pentyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 2,2-dimethylpropyl group, a n-hexyl group, a 2-hexyl group, a 3-hexyl group, a n-heptyl group, a n-octyl group, a 2-methylpentyl group, a 3-methylpentyl group, a 4-methylpentyl group, a 2-methylpentan-3-yl group, and a n-nonyl group.

The number of carbon atoms in the alkenyl group is preferably 2 to 14, and more preferably 4 to 12 because a more suitable viscosity can be obtained and an increase in viscosity of varnish can be more reliably controlled.

Examples of the linear or branched alkenyl group include a vinyl group, an allyl group, a 4-pentenyl group, an isopropenyl group, an isopentenyl group, a 2-heptenyl group, a 2-octenyl group, and a 2-nonenyl group.

In the formula (1), each n₁ independently represents an integer of 1 to 10.

The bismaleimide compound (A) has maleimide groups at both ends of the molecular chain. The term “both ends” means both ends of the molecular chain of the bismaleimide compound (A), and for example, when the structural unit represented by the formula (1) is present at an end of the molecular chain of the bismaleimide compound (A), the maleimide group is present at an end of the molecular chain of R₁, at an end of the molecular chain on the N atom of the maleimide ring, or at each of both the ends. The bismaleimide compound (A) may have maleimide groups at positions other than both ends of the molecular chain.

The maleimide group is represented by the formula (14), and the N atom is bonded to the molecular chain of the bismaleimide compound (A). In addition, the maleimide groups bonded to the bismaleimide compound (A) may be all the same or different, and the maleimide groups at both ends of the molecular chain are preferably the same.

In the formula (14), each R₂₁ independently represents a hydrogen atom, or a linear or branched alkyl group having 1 to 4 carbon atoms. Each R₂₁ is preferably a hydrogen atom because photocuring is suitably performed.

The number of carbon atoms in the alkyl group is preferably 1 to 3, and more preferably 1 or 2 because photocuring is suitably performed.

For the linear or branched alkyl group, R₃ can be referred to.

Examples of such a bismaleimide compound (A) include a maleimide compound represented by the formula (15). One of these bismaleimide compounds can be used, or two or more thereof can be appropriately mixed and used.

In the formula (15), a represents an integer of 1 to 10. a is preferably an integer of 1 to 6 because a more suitable viscosity can be obtained and an increase in viscosity of varnish can be more reliably controlled.

As the bismaleimide compound (A), commercial products can also be used. Examples of the commercial products include MIZ-001 manufactured by Nippon Kayaku Co., Ltd. (product name, containing the maleimide compound of the formula (15)).

In the resin composition, the content of the bismaleimide compound (A) is preferably 10 to 90 parts by mass, more preferably 20 to 80 parts by mass, and still more preferably 35 to 75 parts by mass based on 100 parts by mass of the total of the bismaleimide compound (A) and the later-described maleimide compounds (B), from the viewpoint that the compatibility with the later-described maleimide compounds (B) becomes better, it becomes possible to obtain a cured product mainly composed of the bismaleimide compounds, photocurability can be improved, superior heat resistance and thermal stability can be obtained, and furthermore, a resin sheet having more satisfactorily suppressed tackiness can be obtained.

One of these bismaleimide compounds (A) can be used, or two or more thereof can be appropriately mixed and used.

(Method for Producing Bismaleimide Compound (A))

The bismaleimide compound (A) can be produced by a known method. For example, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, a monomer containing a diamine including a dimer diamine or the like, and maleic anhydride are subjected to a polyaddition reaction at a temperature of normally about 80 to 250° C., preferably about 100 to 200° C. for normally about 0.5 to 50 hours, preferably about 1 to 20 hours to obtain a polyaddition product, and the polyaddition product is then subjected to an imidization reaction, i.e. a ring closure reaction with dehydration at a temperature of normally about 60 to 120° C., preferably about 80 to 100° C. for normally about 0.1 to 2 hours, preferably about 0.1 to 0.5 hours to obtain the bismaleimide compound (A).

The dimer diamine can be obtained by, for example, a reductive amination reaction of a dimer acid, and the amination reaction can be conducted by, for example, a known method such as a reduction method using ammonia and a catalyst (e.g. the method described in Japanese Patent Laid-Open No. 9-12712). The dimer acid is a dibasic acid obtained by dimerization of an unsaturated fatty acid through an intermolecular polymerization reaction or the like. Depending on synthesis conditions and purification conditions, a small amount of monomer acids, trimer acids, or the like are normally contained in addition to the dimer acid. After the reaction, double bonds remain in the obtained molecule, and in the present embodiment, the dimer acids also include those formed into saturated dibasic acids by reduction of double bonds present in the molecule through a hydrogenation reaction. The dimer acid can be obtained by, for example, polymerizing an unsaturated fatty acid using Lewis acid and Broensted acid as catalysts. The dimer acid can be produced by a known method (e.g. the method described in Japanese unexamined Patent Application Publication No. 9-12712). Examples of the unsaturated fatty acid include crotonic acid, myristoleic acid, palmitoleic acid, oleic acid, elaidic acid, vaccenic acid, gadoleic acid, eicosenoic acid, erucic acid, nervonic acid, linoleic acid, pinolenic acid, eleostearic acid, mead acid, dihomo-γ-linolenic acid, eicosatrienoic acid, stearidonic acid, arachidonic acid, eicosatetraenoic acid, adrenic acid, bosseopentaenoic acid, Osbond acid, clupanodonic acid, tetracosapentaenoic acid, docosahexaenoic acid, and Nisinic acid. The number of carbon atoms in the unsaturated fatty acid is normally 4 to 24, and preferably 14 to 20.

In production of the bismaleimide compound (A), it is preferable that the monomer containing a diamine be dissolved or dispersed in a slurry form in an organic solvent in an inert atmosphere of, for example, argon, nitrogen or the like to form a monomer solution containing a diamine in advance. It is preferable that the 1,2,4,5-cyclohexanetetracarboxylic dianhydride be added to the monomer solution containing a diamine after being dissolved or dispersed in a slurry form in an organic solvent, or in a solid state.

A desired bismaleimide compound (A) can be obtained by adjusting the number of moles of the 1,2,4,5-cyclohexanetetracarboxylic dianhydride and the number of moles of the total amount of the monomer containing a diamine and the maleimide compound.

Various known solvents can be used for the polyaddition reaction and the imidization reaction. Examples of the solvent include amides such as N,N-dimethylformamide, N,N-dimethylacetamide and N-methyl-2-pyrrolidone; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and isophorone; esters such as γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-caprolactone, α-methyl-γ-butyrolactone, ethyl lactate, methyl acetate, ethyl acetate and butyl acetate; aliphatic alcohols having 1 to 10 carbon atoms such as methanol, ethanol and propanol; aromatic group-containing phenols such as phenol and cresol; aromatic group-containing alcohols such as benzyl alcohol; glycols such as ethylene glycol and propylene glycol, monoethers or diethers of these glycols and methanol, ethanol, butanol, hexanol, octanol, benzyl alcohol, phenol, cresol and the like, or glycol ethers such as esters of these monoethers; ethers such as dioxane and tetrahydrofuran; cyclic carbonates such as ethylene carbonate and propylene carbonate; aliphatic hydrocarbons and aromatic hydrocarbons such as toluene and xylene; and aprotic polar solvents such as dimethylsulfoxide. One of these solvents can be used, or two or more thereof can be combined and used if required.

It is preferable to use a catalyst in the imidization reaction. As the catalyst, for example, tertiary amines and dehydration catalysts can be used. The tertiary amine is preferably a heterocyclic tertiary amine, and examples thereof include pyridine, picoline, quinoline and isoquinoline. Examples of the dehydration catalyst include acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride and trifluoroacetic anhydride.

For the amount of the catalyst added, it is preferable that for example, the amount of an imidizing agent be about 0.5 to 5.0 times the amount of amide groups on a molar basis, and the amount of the dehydration catalyst be 0.5 to 10.0 times the amount of amide groups on a molar basis.

After completion of the imidization reaction, the solution may be used as a bismaleimide compound (A) solution, or a poor solvent may be added to the reaction solvent to form the bismaleimide compound (A) into a solid matter. Examples of the poor solvent include water, methyl alcohol, ethyl alcohol, 2-propyl alcohol, ethylene glycol, triethylene glycol, 2-butyl alcohol, 2-pentyl alcohol, 2-hexyl alcohol, cyclopentyl alcohol, cyclohexyl alcohol, phenol and t-butyl alcohol.

<Maleimide Compound (B)>

The resin composition of the present embodiment contains maleimide compounds (B) (also referred to as components (B)) other than the bismaleimide compound (A) according to the present embodiment. The maleimide compounds (B) are at least two selected from the group consisting of a compound represented by the formula (2), a compound represented by the formula (3), a compound represented by the formula (4), a compound represented by the formula (5), a compound represented by the formula (6), and a compound represented by the formula (7). As the maleimide compounds (B), two or more of the compounds represented by the formulas (2) to (7) can be appropriately mixed and used. The resin composition preferably contains two to four, and more preferably contains two of the compounds represented by the formulas (2) to (7) as the maleimide compounds (B) because the bismaleimide compound (A) and the maleimide compounds (B) can have better solubility, liquid components in the varnish can be more reduced while the resin composition has superior photocurability, and a resin sheet having more satisfactorily suppressed tackiness can be obtained.

As mentioned above, normally, the reactivity of maleimide compounds towards photo radical is very low. However, the bismaleimide compound (A) has superior light transmissivity as mentioned above. Therefore, by using the bismaleimide compound (A) together with the maleimide compounds (B), as well as the later-described photo initiator (C) and the later-described compound (D) containing one or more carboxyl groups which are compounded if required, light reaches the photo initiator sufficiently, the photo radical reaction of the maleimide efficiently takes place, and these compounds can be photocured using various active energy rays.

Since the bismaleimide compound (A) has excellent light transmissivity, light reaches the photo initiator sufficiently, for example, even when an active energy ray including a wavelength of 365 nm or an active energy ray including a wavelength of 405 nm is used, radical reaction using radicals generated from the photo initiator proceeds, and even a composition containing the maleimide compounds (B) can be photocured.

The maleimide compounds (B) have good compatibility with the bismaleimide compound (A) and have excellent solubility in an organic solvent. Meanwhile, when varnish is fabricated using the maleimide compounds (B) together with the bismaleimide compound (A), the maleimide compounds (B) can suitably suppress the proportion of the liquid components in the system, so that the tackiness of the resin sheet obtained by drying the varnish can be satisfactorily suppressed. Furthermore, since a cured material obtained has excellent heat resistance, insulation reliability, and thermal stability, a protective film and an insulation layer can be suitably formed according to the resin composition of the present embodiment.

Then, the compounds represented by the formulas (2) to (7) included in the maleimide compounds (B) will be described.

(Compound Represented by Formula (2))

The compound represented by the formula (2) is the following compound.

In the formula (2), each of R₄, R₅, and R₆ independently represents a hydrogen atom, a hydroxyl group, or a linear or branched alkyl group having 1 to 6 carbon atoms and optionally having a substituent. n₂ represents an integer of 1 to 10.

For the linear or branched alkyl group having 1 to 6 carbon atoms, R₃ in the formula (1) can be referred to. The alkyl group is preferably a methyl group, an ethyl group, a n-propyl group, or an isopropyl group, and more preferably a methyl group from the viewpoint of exhibiting good solubility in a solvent, a low melting point, low water absorbency, and good compatibility with other resins.

For R₄, R₅, and R₆, it is preferable that R₄ and R₆ be a linear or branched alkyl group having 1 to 6 carbon atoms and R₅ be a hydrogen atom from the viewpoint of exhibiting superior solubility in a solvent. The preferable alkyl group is as defined above.

n₂ is preferably an integer of 1 to 10, and more preferably an integer of 1 to 6 because the solubility in a solvent is excellent, a more suitable viscosity can be obtained, and an increase in viscosity of varnish can be more reliably controlled.

As the compound represented by the formula (2), commercial products can also be used. Examples thereof include BCPH13 (product name) manufactured by Gunei Chemical Industry Co., Ltd. and BCPH01 (product name) manufactured by Gunei Chemical Industry Co., Ltd. which are represented by the formula (16), or BMCX426 (product name) manufactured by Gunei Chemical Industry Co., Ltd. which is represented by the formula (17).

In the above formula (16), n₂₁ is an integer of 1 to 5.

In the formula (17), n₂₂ is an integer of 1 to 10.

(Compound Represented by Formula (3))

The compound represented by the formula (3) is the following compound.

In the formula (3), each R₇ independently represents a hydrogen atom or a methyl group. n₃ represents an integer of 1 to 10.

As the maleimide compound represented by the formula (3), commercial products can also be used. Examples thereof include MIR-3000 (product name) manufactured by Nippon Kayaku Co., Ltd. which is represented by the formula (18).

In the formula (18), n₃₁ is an integer of 1 to 10.

(Compound Represented by Formula (4))

The compound represented by the formula (4) is the following compound.

In the formula (4), each of R₈, R₉, and R₁₀ independently represents a hydrogen atom, or a linear or branched alkyl group having 1 to 8 carbon atoms and optionally having a substituent.

Examples of the linear or branched alkyl group having 1 to 8 carbon atoms and optionally having a substituent include, but are not particularly limited to, a methyl group, an ethyl group, a propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a tert-butyl group, a n-pentyl group, a 1-ethylpropyl group, a 2,2-dimethylpropyl group, a cyclopentyl group, a hexyl group, and a heptyl group. A hydrogen atom in these alkyl groups may be replaced by a halogen atom such as a fluorine atom or a chlorine atom, or a cyano group or the like. Among these alkyl groups, a methyl group, an ethyl group, an isopropyl group, and a tert-butyl group are preferable, a methyl group, an ethyl group, and a tert-butyl group are more preferable, and a methyl group is still more preferable from the viewpoint of having superior photocurability, heat resistance, and thermal stability, and having better solubility in a solvent.

The compound represented by the formula (4) is further more preferably a compound represented by the formula (19) (also referred to as TMDM, in the present embodiment) from the viewpoint of having superior photocurability, heat resistance, and thermal stability, and having better solubility in a solvent.

(Compound Represented by Formula (5))

The compound represented by the formula (5) is the following compound.

In the formula (5), each R₁₁ independently represents a hydrogen atom, a methyl group, or an ethyl group, and each R₁₂ independently represents a hydrogen atom or a methyl group.

R₁₁ is preferably a methyl group or an ethyl group from the viewpoint of exhibiting good solubility in a solvent, a low boiling point, low water absorbency, and good compatibility with other resins.

R₁₂ is preferably a hydrogen atom from the viewpoint of exhibiting good solubility in a solvent, a low boiling point, low water absorbency, and good compatibility with other resins.

As the maleimide compound represented by the formula (5), commercial products can also be used. Examples thereof include BMI-70 (product name) manufactured by K·I Chemical Industry Co., LTD. which is represented by the formula (20).

(Compound Represented by Formula (6))

The compound represented by the formula (6) is the following compound.

In the formula (6), each R₁₃ independently represents a hydrogen atom, a methyl group, or an ethyl group.

R₁₃ is preferably a methyl group or an ethyl group from the viewpoint of exhibiting good solubility in a solvent, a low boiling point, low water absorbency, and good compatibility with other resins.

As the maleimide compound represented by the formula (6), commercial products can also be used. Examples thereof include BMI-80 (product name) manufactured by K·I Chemical Industry Co., LTD. which is represented by the formula (21).

(Compound Represented by Formula (7))

The compound represented by the formula (7) is the following compound.

In the formula (7), each R₁₄ independently represents a hydrogen atom or a methyl group. n₄ represents an integer of 1 to 10.

R₁₄ is preferably a hydrogen atom from the viewpoint of exhibiting good solubility in a solvent, a low boiling point, low water absorbency, and good compatibility with other resins.

n₄ is more preferably an integer of 1 to 5 because the solubility in a solvent is excellent, a more suitable viscosity can be obtained, and an increase in viscosity of varnish can be more reliably controlled.

As the maleimide compound represented by the formula (7), commercial products can also be used. Examples thereof include BMI-2300 (product name) manufactured by Daiwa Kasei Industry Co., LTD. which is represented by the formula (22).

In the formula (22), n₄₁ is an integer of 1 to 5.

In the resin composition, the content of the maleimide compounds (B) is preferably 10 to 90 parts by mass, more preferably 20 to 80 parts by mass, and still more preferably 25 to 65 parts by mass based on 100 parts by mass of the total of the bismaleimide compound (A) and the maleimide compounds (B), from the viewpoint that the compatibility with the bismaleimide compound (A) becomes better, superior heat resistance and thermal stability can be obtained, and furthermore, a resin sheet having more satisfactorily suppressed tackiness can be obtained.

<Photo Initiator (C)>

It is preferable that the resin composition of the present embodiment further contain the photo initiator (C) (also referred to as component (C)). The photo initiator (C) is not particularly limited, and photo initiators can be used which are publicly known in fields where photo initiators are generally used for photocurable resin compositions. The photo initiator (C) can be photocured together with the bismaleimide compound (A), the maleimide compounds (B), the later-described compound (D) containing one or more carboxyl groups, and the like using various active energy rays.

Examples of the photo initiator (C) include radical type photo initiators such as benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether and benzoin isobutyl ether; organic peroxides exemplified by benzoyl peroxide, lauroyl peroxide, acetyl peroxide, parachlorobenzoyl peroxide, di-tert-butyl-di-perphthalate and the like; phosphine oxides such as 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, benzoyl-diphenyl-phosphine oxide and bisbenzoyl-phenyphosphine oxide; acetophenones such as acetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 2-hydroxy-2-methyl-phenylpropan-1-one, diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1; anthraquinones such as 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-chloroanthraquinone and 2-amylanthraquinone; thioxanthones such as 2,4-diethylthioxanthone, 2-isopropylthioxanthone and 2-chlorothioxanthone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzophenones such as benzophenone, 4-benzoyl-4′-methyldiphenyl sulfide and 4,4′-bismethylaminobenzophenone; and oxime esters such as 1,2-octanedione, 1-[4-(phenylthio)-2-(O-benzoyloxime)] and ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime);

diazonium salts of Lewis acid such as p-methoxyphenyldiazonium fluorophosphonate and N,N-diethylaminophenyldiazonium hexafluorophosphonate; iodonium salts of Lewis acid such as diphenyliodonium hexafluorophosphonate and diphenyliodonium hexafluoroantimonate; sulfonium salts of Lewis acid such as triphenylsulfonium hexafluorophosphonate and triphenylsulfonium hexafluoroantimonate; phosphonium salts of Lewis acid such as triphenylphosphonium hexafluoroantimonate; additional halides; triazine-based initiators; borate-based initiators; and cationic photo initiators such as additional photoacid generators.

As the photo initiator (C), commercial products can also be used. Examples thereof include Omnirad (registered trademark) 369 (product name) manufactured by IGM Resins B.V., Omnirad (registered trademark) 819 (product name) manufactured by IGM Resins B.V., Omnirad (registered trademark) 819DW (product name) manufactured by IGM Resins B.V., Omnirad (registered trademark) 907 (product name) manufactured by IGM Resins B.V., Omnirad (registered trademark) TPO (product name) manufactured by IGM Resins B.V., Omnirad (registered trademark) TPO-G (product name) manufactured by IGM Resins B.V., Omnirad (registered trademark) 784 (product name) manufactured by IGM Resins B.V., Irgacure (registered trademark) OXE01 (product name) manufactured by BASF Japan Ltd., Irgacure (registered trademark) OXE02 (product name) manufactured by BASF Japan Ltd., Irgacure (registered trademark) OXE03 (product name) manufactured by BASF Japan Ltd., and Irgacure (registered trademark) OXE04 (product name) manufactured by BASF Japan Ltd.

One of these photo initiators (C) can be used, or two or more thereof can be appropriately mixed and used.

The photo initiator (C) has an absorbance of preferably 0.1 or more when a chloroform solution containing the photo initiator (C) at 0.01% by mass is prepared, and the absorbance of the chloroform solution containing the photo initiator (C) at 0.01% by mass is measured using an active energy ray including a wavelength of 365 nm (i-line). In this case, the photo initiator (C) exhibits superior light absorption. In addition, the photo initiator (C) has an absorbance of preferably 0.1 or more when the absorbance of a chloroform solution containing the photo initiator (C) at 0.01% by mass is measured using an active energy ray including a wavelength of 405 nm (h-line). Even in this case, superior light absorption is exhibited. When such a photo initiator (C) is used, for example, upon producing a printed wiring board having a highly dense and highly detailed wiring formation (pattern) using the direct imaging method, the photo radical reaction of the maleimide occurs efficiently even when an active energy ray including a wavelength of 405 nm (h-line) is used. The absorbance at a wavelength of 365 nm (i-line) is more preferably 0.15 or more because a resin composition that is superior in photocurability can be obtained. The absorbance at a wavelength of 405 nm (h-line) is more preferably 0.15 or more because a resin composition that is superior in photocurability can be obtained. The upper limit of each of the absorbance at a wavelength of 365 nm (i-line) and the absorbance at a wavelength of 405 nm (h-line) is, for example, 99.9 or less.

As such a photo initiator (C), a compound represented by the formula (8) is preferable.

In the formula (8), each R₁₅ independently represents a substituent represented by the formula (9) or a phenyl group.

In the formula (9), each R₁₆ independently represents a hydrogen atom or a methyl group. In the formula (9), -* indicates a bonding hand to a phosphorus atom (P) directly bonded to R₁₅ in the formula (8).

As for the compound represented by the formula (9), when a chloroform solution containing this compound at 0.01% by mass is prepared and the absorbance of this chloroform solution is measured using an active energy ray including a wavelength of 365 nm (i-line), the absorbance is 0.1 or more, exhibiting superior absorption of the light with a wavelength of 365 nm (i-line). Therefore, this compound suitably generates radicals in response to the light with a wavelength of 365 nm (i-line). The absorbance is preferably 0.15 or more. The upper limit value is, for example, 10.0 or less, and may be 5.0 or less, or 2.0 or less.

As for the compound represented by the formula (8), when a chloroform solution containing this compound at 0.01% by mass is prepared and the absorbance of this chloroform solution is measured using an active energy ray including a wavelength of 405 nm (h-line), the absorbance is 0.1 or more, exhibiting superior absorption of the light with a wavelength of 405 nm (h-line). Therefore, this compound suitably generates radicals in response to the light with a wavelength of 405 nm (h-line). The absorbance is more preferably 0.15 or more. The upper limit value is, for example, 10.0 or less, and may be 5.0 or less, or 2.0 or less.

In the formula (8), each R₁₅ independently represents a substituent represented by the formula (9) or a phenyl group. It is preferable that one or more among R₁₅s be the substituents represented by the formula (9).

In the formula (9), each R₁₆ independently represents a hydrogen atom or a methyl group. It is preferable that one or more among R₁₆s be methyl groups, and it is more preferable that all should be methyl groups.

Examples of the compound represented by the formula (8) include acylphosphine oxides such as 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide. Among the above, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide is preferable because it has excellent light transmissivity. One of these compounds can be used, or two or more thereof can be appropriately mixed and used.

Acylphosphine oxides exhibit superior absorption of an active energy ray including a wavelength of 405 nm (h-line) and can suitably radical polymerize the bismaleimide compound (A) and the maleimide compounds (B), for example, at a wavelength of 405 nm (h-line). In addition, acylphosphine oxides are satisfactorily compatible with the bismaleimide compound (A) and the maleimide compounds (B) and satisfactorily dissolve in an organic solvent. Furthermore, since acylphosphine oxides can be present as a solid after the solvent in the varnish is removed, liquid components in the varnish can be more reduced. Therefore, a resin composition that is superior in solubility and photocurability, and a resin sheet having excellent photocurability and satisfactorily suppressed tackiness can be suitably obtained by using acylphosphine oxides. In addition, a multilayer printed wiring board and a semiconductor device using them can be suitably produced.

In the resin composition, the content of the photo initiator (C) is preferably 0.1 to 50 parts by mass, more preferably 0.2 to 30 parts by mass, and still more preferably 0.3 to 10 parts by mass based on 100 parts by mass of the total of the bismaleimide compound (A) and the maleimide compounds (B), from the viewpoint that the compatibility with the bismaleimide compound (A) and the maleimide compounds (B) becomes better, photocuring of these compounds sufficiently proceeds, the exposed portion is sufficiently insolubilized in alkaline developability, and furthermore, a resin sheet having more satisfactorily suppressed tackiness can be obtained.

<Compound (D) Containing One or More Carboxy Groups>

It is preferable that the resin composition of the present embodiment further contain the compound (D) containing one or more carboxyl groups (also referred to as component (D) or compound (D)). The compound (D) is not particularly limited as long as it contains one or more carboxy groups in the compound. The carboxy group may be a salt such as a sodium salt or a potassium salt, and when two or more carboxy groups are contained in the molecule, the carboxy groups may be linked together to form an acid anhydride. One of the compounds (D) can be used, or two or more thereof can be appropriately mixed and used.

A cured product can be obtained by photocuring the compound (D) together with the bismaleimide compound (A) and the maleimide compounds (B) according to the present embodiment, and if required, the photo initiator (C) using various active energy rays. In addition, according to the present embodiment, it is possible to obtain a resin composition containing the compound (D) in an unexposed portion.

The compound (D) has a transmittance of preferably 5% or more when a N-methylpyrrolidone solution containing the compound (D) at 1% by mass is prepared and the transmittance of the N-methylpyrrolidone solution containing the compound (D) at 1% by mass is measured using an active energy ray including a wavelength of 365 nm (i-line). Thus, the compound (D) exhibits superior light transmissivity. In addition, the compound (D) has a transmittance of preferably 5% or more when the transmittance of a N-methylpyrrolidone solution containing the compound (D) at 1% by mass is measured using an active energy ray including a wavelength of 405 nm (h-line). Even in this case, superior light transmissivity is exhibited. When such a compound (D) is used, for example, upon producing a printed wiring board having a highly dense and highly detailed wiring formation (pattern) using the direct imaging method, the photo radical reaction of the maleimide occurs efficiently even when an active energy ray including a wavelength of 405 nm (h-line) is used. The transmittance at a wavelength of 365 nm (i-line) is preferably 8% or more, more preferably 10% or more, still more preferably 20% or more, even more preferably 30% or more, and furthermore preferably 40% or more because a resin composition that is superior in photocurability can be obtained. The transmittance at a wavelength of 405 nm (h-line) is preferably 8% or more, more preferably 10% or more, still more preferably 20% or more, even more preferably 30% or more, and furthermore preferably 40% or more because a resin composition that is superior in photocurability can be obtained. The upper limit of each of the transmittance at a wavelength of 365 nm (i-line) and the transmittance at a wavelength of 405 nm (h-line) is, for example, 99.9% or less.

In the present embodiment, it is preferable that the molecule of the compound (D) contain n carboxy groups where n is an integer of 2 to 4 because superior alkaline developability can be obtained.

The molecular weight of the compound (D) is preferably 50 to 1000, and more preferably 100 to 800 because developability is further improved.

Examples of the compound (D) include formic acid, aliphatic compounds containing one or more carboxy groups, aromatic compounds containing one or more carboxy groups, and hetero compounds containing one or more carboxy groups. One of these compounds (D) can be used, or two or more thereof can be appropriately mixed and used.

(Aliphatic Compound Containing One or More Carboxy Groups)

Examples of the aliphatic compound containing one or more carboxy groups include chain aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, chain aliphatic polyvalent carboxylic acids and alicyclic polyvalent carboxylic acids. These compounds may have hydrogen atoms and substituents such as alkyl groups, alkoxy groups, aryloxy groups, aryl groups, aminoalkyl groups, hydroxyl groups, amino groups and carboxyalkyl groups in the molecule. When these compounds have two or more carboxy groups in the molecule, the carboxy groups may be linked together to form an acid anhydride. When these compounds have a carboxyalkyl group in the molecule, the carboxyalkyl group and the carboxy group may be linked together to form an acid anhydride. When these compounds have two or more carboxyalkyl groups in the molecule, the carboxyalkyl groups may be linked together to form an acid anhydride.

Examples of the alkyl group include a methyl group, an ethyl group, a n-propyl group, an i-propyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, a n-hexyl group, a n-heptyl group and a n-octyl group.

Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a n-butoxy group, an isobutoxy group, a tert-butoxy group, a n-hexanoxy group and a 2-methylpropoxy group.

Examples of the aryloxy group include a phenoxy group and a p-tolyloxy group.

Examples of the aryl group include a phenyl group, a toluyl group, a benzyl group, a methylbenzyl group, a xylyl group, a mesityl group, a naphthyl group and an anthryl group.

Examples of the aminoalkyl group include an aminomethyl group, an aminoethyl group, an aminopropyl group, an aminodimethyl group, an aminodiethyl group, an aminodipropyl group, an aminobutyl group, an aminohexyl group and an aminononyl group.

Examples of the carboxyalkyl group include a carboxymethyl group, a carboxyethyl group, a carboxypropyl group, a carboxybutyl group, a carboxyhexyl group and a carboxynonyl group.

Examples of the chain aliphatic monocarboxylic acid include saturated fatty acids such as acetic acid, propionic acid, isobutyric acid, butyric acid, isovaleric acid, valeric acid, caproic acid, lactic acid, succinic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, heptadecanoic acid and octadecanoic acid, and unsaturated fatty acids such as oleic acid, elaidic acid, erucic acid, nervonic acid, linolenic acid, stearidonic acid, eicosapentaenoic acid, linoleic acid and linolenic acid.

Examples of the alicyclic monocarboxylic acid include monocyclic carboxylic acids such as cyclopropanecarboxylic acid, cyclopropenecarboxylic acid, cyclobutanecarboxylic acid, cyclobutenecarboxylic acid, cyclopentanecarboxylic acid, cyclopentenecarboxylic acid, cyclohexanecarboxylic acid, cyclohexenecarboxylic acid, cycloheptanecarboxylic acid, cycloheptenecarboxylic acid, cyclooctanecarboxylic acid and cyclooctenecarboxylic acid, and polycyclic or bridged alicyclic carboxylic acids such as norbornanecarboxylic acid, tricyclodecanecarboxylic acid, tetracyclododecanecarboxylic acid, adamantanecarboxylic acid, methyladamantanecarboxylic acid, ethyladamantanecarboxylic acid and butyladamantanecarboxylic acid.

Examples of the chain aliphatic polyvalent carboxylic acid include carboxylic acids in which one or more carboxy groups are further added to a chain aliphatic monocarboxylic acid. Examples thereof include propionedioic acid, octanedioic acid, nonanedioic acid, decanedioic acid, dodecanedioic acid, tetradecanedioic acid, hexadecanedioic acid, heptadecanedioic acid and octadecanedioic acid.

Examples of the aliphatic polyvalent carboxylic acid include carboxylic acids in which one or more carboxy groups are further added to an alicyclic monocarboxylic acid. Examples thereof include monocyclic carboxylic acids such as cyclopropanedicarboxylic acid, cyclopropenedicarboxylic acid, cyclopropanetricarboxylic acid, cyclopropenetricarboxylic acid, cyclobutanedicarboxylic acid, cyclobutenedicarboxylic acid, cyclobutanetricarboxylic acid, cyclobutenetricarboxylic acid, cyclobutanetetracarboxylic acid, cyclobutenetetracarboxylic acid, cyclopentanedicarboxylic acid, cyclopentenedicarboxylic acid, cyclopentanetricarboxylic acid, cyclopentenetricarboxylic acid, cyclopentanetetracarboxylic acid, cyclopentenetetracarboxylic acid, cyclopentanepentacarboxylic acid, cyclopentenepentacarboxylic acid, cyclohexanedicarboxylic acid, cyclohexenedicarboxylic acid, cyclohexanetricarboxylic acid, cyclohexenetricarboxylic acid, cyclohexanetetraboxylic acid, cyclohexenetetracarboxylic acid, cyclohexanepentacarboxylic acid, cyclohexenepentacarboxylic acid, cyclohexanehexacarboxylic acid, cyclohexenehexacarboxylic acid, cycloheptanedicarboxylic acid, cycloheptenedicarboxylic acid, cyclooctanedicarboxylic acid and cyclooctenedicarboxylic acid, and polycyclic or bridged alicyclic carboxylic acids such as norbornanedicarboxylic acid and adamantanedicarboxylic acid.

(Aromatic Compound Containing One or More Carboxy Groups)

Examples of the main backbone of the aromatic compound containing one or more carboxy groups include benzoic acid, phenyleneacetic acid, salicylic acid, phthalic acid, trimellitic acid, pyromellitic acid, pentacarboxybenzene, hexacarboxybenzene, naphthalenecarboxylic acid, naphthalenedicarboxylic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, anthracenecarboxylic acid, anthracenedicarboxylic acid, anthracenetricarboxylic acid, anthracenetetracarboxylic acid and anthracenepentacarboxylic acid. The aromatic compound may have, for example, hydrogen atoms and substituents such as alkyl groups, alkoxy groups, aryloxy groups, aryl groups, aminoalkyl groups, hydroxyl groups, amino groups and carboxyalkyl groups on the aromatic ring of the main backbone. When these compounds have two or more carboxy groups in the molecule, the carboxy groups may be linked together to form an acid anhydride. When these compounds have a carboxyalkyl group in the molecule, the carboxyalkyl group and the carboxy group may be linked together to form an acid anhydride. When these compounds have two or more carboxyalkyl groups in the molecule, the carboxyalkyl groups may be linked together to form an acid anhydride. For these substituents, those described above can be referred to.

(Hetero Compound Containing One or More Carboxy Groups)

Examples of the main backbone of the hetero compound containing one or more carboxy groups include compounds containing one or more carboxy groups on hetero rings such as furan, thiophene, pyrrole, imidazole, pyran, pyridine, pyrimidine, pyrazine, pyrrolidine, piperidine, piperazine, morpholine, indole, purine, quinoline, isoquinoline, quinuclidine, chromene, thianthrene, phenothiazine, phenoxazine, xanthene, acridine, phenazine and carbazole. The hetero compound may have, for example, hydrogen atoms and substituents such as alkyl groups, alkoxy groups, aryloxy groups, aryl groups, aminoalkyl groups, hydroxyl groups, amino groups and carboxyalkyl groups on the main backbone. When these compounds have two or more carboxy groups in the molecule, the carboxy groups may be linked together to form an acid anhydride. When these compounds have a carboxyalkyl group in the molecule, the carboxyalkyl group and the carboxy group may be linked together to form an acid anhydride. When these compounds have two or more carboxyalkyl groups in the molecule, the carboxyalkyl groups may be linked together to form an acid anhydride. For these substituents, those described above can be referred to.

The compound (D) is preferably any of a compound represented by the formula (10), a compound represented by the formula (11), a compound represented by the formula (12) and a compound represented by the formula (13), in view of imparting superior alkaline developability to the resin composition, and more preferably a compound represented by the formula (12), in view of imparting further superior alkaline developability to the resin composition.

The compound represented by the formula (10) is as follows.

In the formula (10), each R₁₇ independently represents a hydrogen atom, a hydroxyl group, a carboxy group, an amino group or an aminomethyl group. When the compound represented by the formula (10) has two or more carboxy groups, the carboxy groups may be linked together to form an acid anhydride. In the formula (10), the upper limit of the number of carboxy groups is 6.

Each R₁₇ is independently preferably a hydrogen atom, a hydroxyl group, a carboxy group or an amino group from the viewpoint of alkaline developability, and more preferably includes a carboxy group because superior alkaline developability can be obtained.

The benzoic acid tends to be inferior in alkaline developability to the compound (D) containing one or more other carboxy groups.

Each k independently represents an integer of 1 to 5.

The compound represented by the formula (10) is preferably a compound represented by the formula (23) because superior alkaline developability can be obtained.

In the formula (23), each R₁₇ independently represents a hydrogen atom, a hydroxyl group, an amino group or an aminomethyl group. R₁₇ is preferably a hydrogen atom or a hydroxyl group, and more preferably a hydrogen atom because superior alkaline developability is exhibited.

Each k independently represents an integer of 0 to 4. The number of carboxy groups (p) is an integer of 5-k. The number of carboxy groups (p) is preferably an integer of 1 to 3 because superior alkaline developability is exhibited. In this case, the number of R₁₇s (k) is an integer of 5−p, which is an integer of 2 to 4.

The compound represented by the formula (23) may contain two or more carboxy groups, with the carboxy groups being linked together to form an acid anhydride.

Examples of the compound represented by the above formula (10) include 4-aminobenzoic acid, salicylic acid, phthalic acid, trimellitic acid, pyromellitic acid, 4-aminomethylbenzoic acid and anhydrides thereof. Examples of these anhydrides include phthalic anhydride, trimellitic anhydride and pyromellitic anhydride. The compound represented by the formula (10) is preferably any of phthalic acid, trimellitic acid, pyromellitic acid and anhydrides thereof because superior alkaline developability can be obtained.

The compound represented by the formula (11) is as follows.

In the formula (11), each R₁₈ independently represents a hydrogen atom, a hydroxyl group, a carboxy group, a carboxymethyl group, an amino group or an aminomethyl group. When the compound represented by the formula (11) has two or more carboxy groups, the carboxy groups may be linked together to form an acid anhydride. In the formula (11), the upper limit of the number of carboxy groups is 10. When the compound represented by the formula (11) has a carboxymethyl group, the carboxymethyl group and the carboxy group may be linked together to form an acid anhydride.

Each R₁₈ is independently preferably a hydrogen atom, a hydroxyl group, a carboxy group or an amino group from the viewpoint of alkaline developability, and more preferably includes a carboxy group because superior alkaline developability can be obtained.

Each 1 independently represents an integer of 1 to 9.

The piperidinecarboxylic acid tends to be inferior in alkaline developability to the compound (B) containing one or more other carboxy groups.

When a carboxy group is contained as R₁₈, the number of carboxy groups (1) is preferably 1 to 3 from the viewpoint of alkaline developability. Each R₅ other than carboxy groups is independently preferably a hydrogen atom or a hydroxyl group, and more preferably a hydrogen atom. When the compound represented by the formula (11) contains one to three carboxy groups, the number of R₅s other than carboxy groups is 7 to 9.

Examples of the compound represented by the formula (11) include piperidinecarboxylic acid, 1,2-piperidinecarboxylic acid and piperidinedicarboxylic anhydride.

The compound represented by the formula (12) is as follows.

In the formula (12), each R₁₉ independently represents a hydrogen atom, a hydroxyl group, a carboxy group, a carboxymethyl group, an amino group or an aminomethyl group. When the compound represented by the formula (12) has two or more carboxy groups, the carboxy groups may be linked together to form an acid anhydride. In the formula (12), the upper limit of the number of carboxy groups is 10. When the compound represented by the formula (12) has a carboxymethyl group, the carboxymethyl group and the carboxy group may be linked together to form an acid anhydride.

Each R₁₉ is independently preferably a hydrogen atom, a hydroxyl group, a carboxy group or an amino group from the viewpoint of alkaline developability, and more preferably includes a carboxy group because superior alkaline developability can be obtained.

Each m independently represents an integer of 1 to 9.

The compound represented by the formula (12) is preferably a compound represented by the formula (24) because superior alkaline developability can be obtained.

In the formula (24), each R₁₉ independently represents a hydrogen atom, a hydroxyl group, a carboxymethyl group, an amino group or an aminomethyl group. R₁₉ is preferably a hydrogen atom or a hydroxyl group, and more preferably a hydrogen atom because superior alkaline developability is exhibited.

Each m independently represents an integer of 0 to 8.

The number of carboxy groups (q) is an integer of 9-m. The number of carboxy groups (q) is preferably an integer of 1 to 3 because superior alkaline developability is exhibited. In this case, the number of R₆s (m) is an integer of 9-q, which is an integer of 6 to 8.

The compound represented by the formula (24) may contain two or more carboxy groups, with the carboxy groups being linked together to form an acid anhydride. When the compound represented by the formula (24) has a carboxymethyl group, the carboxymethyl group and the carboxy group may be linked together to form an acid anhydride.

Examples of the compound represented by the formula (12) include 3-cyclohexene-1-carboxylic acid, cis-4-cyclohexene-1,2-dicarboxylic acid and cis-4-cyclohexene-1,2-dicarboxylic anhydride. The compound represented by the formula (12) is preferably any of cis-4-cyclohexene-1,2-dicarboxylic acid and cis-4-cyclohexene-1,2-dicarboxylic anhydride because superior alkaline developability can be obtained.

The compound represented by the formula (13) is as follows.

In the formula (13), each R₂₀ independently represents a hydrogen atom, a hydroxyl group, a carboxy group, a carboxymethyl group, an amino group or an aminomethyl group. When the compound represented by the formula (13) has one or more carboxy groups, the carboxymethyl group and the carboxy group may be linked together to form an acid anhydride. In the formula (13), when two or more carboxy groups are present, the carboxy groups may be linked together to form an acid anhydride. In the formula (13), the upper limit of the number of carboxy groups is 5. In the formula (13), when two or more carboxymethyl groups are present, the carboxymethyl groups may be linked together to form an acid anhydride. In the formula (13), the upper limit of the number of carboxymethyl groups is 6.

Each R₂₀ is independently preferably a hydrogen atom, a hydroxyl group, a carboxy group or an amino group from the viewpoint of alkaline developability, and more preferably includes a carboxy group because superior alkaline developability can be obtained.

Each o independently represents an integer of 1 to 5.

The compound represented by the formula (13) is preferably a compound represented by the formula (25) because superior alkaline developability can be obtained.

In the formula (25), each R₂₀ independently represents a hydrogen atom, a hydroxyl group, a carboxymethyl group, an amino group or an aminomethyl group. R₂₀ is preferably a hydrogen atom or a hydroxyl group, and more preferably a hydrogen atom because superior alkaline developability is exhibited.

Each o independently represents an integer of 0 to 4.

The number of carboxy groups (r) is an integer of 5−o. The number of carboxy groups (r) is preferably an integer of 1 to 3 because superior alkaline developability is exhibited. In this case, the number of R₇s (o) is an integer of 5-r, which is an integer of 2 to 4.

In the formula (25), the carboxymethyl group and the carboxy group may be linked together to form an acid anhydride. When the compound represented by the formula (25) has two or more carboxy groups, the carboxy groups may be linked together to form an acid anhydride. In the formula (25), the upper limit of the number of carboxy groups is 5. When the compound represented by the formula (25) has two or more carboxymethyl groups, the carboxymethyl groups may be linked together to form an acid anhydride. In the formula (25), the upper limit of the number of carboxymethyl groups is 6.

Examples of the compound represented by the above formula (13) include phenyleneacetic acid, 1,2-phenylenediacetic acid, 1,3-phenylenediacetic acid, 1,4-phenylenediacetic acid and anhydrides thereof. Examples of these anhydrides include 1,2-phenylenediacetic anhydride. The compound represented by the formula (13) is preferably a 1,2-phenylenediacetic acid because superior alkaline developability can be obtained.

One of these compounds (D) containing one or more carboxy groups can be used, or two or more thereof can be appropriately mixed and used.

In the resin composition, the content of the compound (D) containing one or more carboxyl groups is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, and still more preferably 1 to 15 parts by mass based on 100 parts by mass of the total of the bismaleimide compound (A) and the maleimide compounds (B), from the viewpoint that the compatibility with the bismaleimide compound (A) and the maleimide compounds (B) becomes better, liquid components in the varnish can be more reduced, and superior alkaline-developability can be imparted.

<Maleimide Compound (E) Other Than Bismaleimide Compound (A) and Maleimide Compounds (B)>

The resin composition of the present embodiment may use a maleimide compound (E) other than the bismaleimide compound (A) and the maleimide compounds (B) (also referred to as component (E)) as long as the effect of the present invention is achieved. The bismaleimide compound (A) has superior light transmissivity, as mentioned above, so that even when the maleimide compound (E) is used together with the maleimide compounds (B), light reaches the photo initiator sufficiently, the photo radical reaction of the maleimide efficiently takes place, and photocuring can be performed using various active energy rays. Therefore, light reaches the photo initiator sufficiently, for example, even when an active energy ray including a wavelength of 365 nm or an active energy ray including a wavelength of 405 nm is used, radical reaction using radicals generated from the photo initiator proceeds, and even a composition containing the maleimide compound (E) can be photocured. As the maleimide compound (E), it is preferable to use a maleimide compound that has better compatibility with the bismaleimide compound (A) and the maleimide compounds (B) and can reduce liquid components in varnish when used in the varnish.

The maleimide compound (E) is not particularly limited as long as it is a compound other than the bismaleimide compound (A) and the maleimide compounds (B), and has one or more maleimide groups in the molecule. Examples thereof include N-phenylmaleimide, N-cyclohexylmaleimide, N-hydroxyphenylmaleimide, N-anilinophenylmaleimide, N-carboxyphenylmaleimide, N-(4-carboxy-3-hydroxyphenyl)maleimide, 6-maleimidehexanoic acid, 4-maleimidebutyric acid, bis(4-maleimidophenyl)methane, 2,2-bis(4-(4-maleimidephenoxy)-phenyl)propane, 4,4-diphenylmethanebismaleimide, bis(3,5-dimethyl-4-maleimidephenyl)methane, bis(3-ethyl-5-methyl-4-maleimidephenyl)methane, bis(3,5-diethyl-4-maleimidephenyl)methane, phenylmethanemaleimide, o-phenylene bismaleimide, m-phenylene bismaleimide, p-phenylene bismaleimide, o-phenylenebiscitraconimido, m-phenylenebiscitraconimido, p-phenylenebiscitraconimido, 2,2-bis(4-(4-maleimidephenoxy)-phenyl)propane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethane bismaleimide, 4-methyl-1,3-phenylenebismaleimide, 1,2-bismaleimideethane, 1,4-bismaleimidebutane, 1,5-bismaleimidepentane, 1,5-bismaleimide-2-methylpentane, 1,6-bismaleimidehexane, 1,6-bismaleimide-(2,2,4-trimethyl)hexane, 1,8-bismaleimide-3,6-dioxaoctane, 1,11-bismaleimide-3,6,9-trioxaundecane, 1,3-bis(maleimide methyl)cyclohexane, 1,4-bis(maleimide methyl)cyclohexane, 4,4-diphenyl ether bismaleimide, 4,4-diphenyl sulfone bismaleimide, 1,3-bis(3-maleimidephenoxy)benzene, 1,3-bis(4-maleimidephenoxy)benzene, 4,4-diphenylmethanebiscitraconimido, 2,2-bis[4-(4-citraconimidophenoxy)phenyl]propane, bis(3,5-dimethyl-4-citraconimidophenyl)methane, bis(3-ethyl-5-methyl-4-citraconimidophenyl)methane, bis(3,5-diethyl-4-citraconimidophenyl)methane, polyphenylmethane maleimide, fluorescein-5-maleimide, and a prepolymer of these maleimide compounds, and a prepolymer of maleimide compounds and amine compounds. One of these maleimide compounds (E) can be used, or two or more thereof can be appropriately mixed and used.

In the resin composition, the content of the maleimide compound (E) is normally 1 to 30 parts by mass based on 100 parts by mass of the total of the bismaleimide compound (A) and the maleimide compounds (B).

<Filler (F)>

In the resin composition of the present embodiment, a filler (F) (also referred to as component (F)) can be used for improving a variety of characteristics such as a coating property and heat resistance. The filler (F) is preferably one that has an insulation property and does not inhibit transmissivity for various active energy rays used for photocuring, and more preferably one that does not inhibit transmissivity for active energy rays including a wavelength of 365 nm (i-line) and/or a wavelength of 405 nm (h-line).

Examples of the filler (F) include silica (for example, natural silica, fused silica, amorphous silica and hollow silica), an aluminum compound (for example, boehmite, aluminum hydroxide, alumina and aluminum nitride), a boron compound (for example, boron nitride), a magnesium compound (for example, magnesium oxide and magnesium hydroxide), a calcium compound (for example, calcium carbonate), a molybdenum compound (for example, molybdenum oxide and zinc molybdate), a barium compound (for example, barium sulfate and barium silicate), talc (for example, natural talc and calcined talc), mica, glass (for example, short fibrous glass, spherical glass, fine powder glass, E glass, T glass and D glass), silicone powder, a fluororesin-based filler, a urethane resin-based filler, a (meth)acrylic resin-based filler, a polyethylene-based filler, a styrene-butadiene rubber, and a silicone rubber. One of these fillers (F) can be used, or two or more thereof can be appropriately mixed and used.

Among the above, it is preferable that the filler (F) should be one or more selected from the group consisting of silica, boehmite, barium sulfate, silicone powder, a fluororesin-based filler, a urethane resin-based filler, a (meth)acrylic resin-based filler, a polyethylene-based filler, a styrene-butadiene rubber, and a silicone rubber.

These fillers (F) may be surface-treated with a silane coupling agent, which will be mentioned later, or the like.

From the viewpoint of improving the heat resistance of the cured product and also obtaining a good coating property, silica is preferable and fused silica is more preferable. Specific examples of the silica include SFP-130MC (product name) manufactured by Denka Company Limited, and SC2050-MB (product name), SC1050-MLE (product name), YA010C-MFN (product name), and YA050C-MJA (product name) manufactured by Admatechs Company Limited.

The particle diameter of the filler (F) is not particularly limited, but from the viewpoint of ultraviolet light transmissivity of the resin composition, it is normally 0.005 to 10 μm, and is preferably 0.01 to 1.0 μm.

In the resin composition, the content of the filler (F) is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, and still more preferably 100 parts by mass or less based on 100 parts by mass of the total of the bismaleimide compound (A) and the maleimide compounds (B) from the viewpoint of improving the light transmissivity of the resin composition and the heat resistance of the cured product. When the filler is contained, the lower limit value of its content is normally 1 part by mass based on 100 parts by mass of the total of the bismaleimide compound (A) and the maleimide compounds (B) from the viewpoint of obtaining effects of improving a variety of characteristics such as a coating property and heat resistance.

<Silane Coupling Agent and Wetting and Dispersing Agent>

In the resin composition of the present embodiment, a silane coupling agent and/or a wetting and dispersing agent can also be used in combination in order to improve the dispersibility of the filler, and the adhesive strength between the polymers and/or the resins and the filler.

The silane coupling agent is not particularly limited as long as it is a silane coupling agent generally used for surface treatment of inorganic matters. Examples thereof include aminosilane-based compounds such as 3-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, 3-aminopropyldimethoxymethylsilane, 3-aminopropyldiethoxymethylsilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyldimethoxymethylsilane, N-(2-aminoethyl)-3-aminopropyldiethoxymethylsilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, [3-(6-aminohexylamino)propyl]trimethoxysilane and [3-(N,N-dimethylamino)propyl]trimethoxysilane; epoxysilane-based compounds such as γ-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, 3-glycidoxypropyldiethoxymethylsilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and [8-(glycidyloxy)-n-octyl]trimethoxysilane; vinylsilane-based compounds such as vinyltris(2-methoxyethoxy)silane, vinyltrimethoxysilane, vinyltriethoxysilane, dimethoxymethylvinylsilane, diethoxymethylvinylsilane, trimethoxy(7-octen-1-yl)silane and trimethoxy(4-vinylphenyl)silane; methacrylic silane-based compounds such as 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropyldimethoxymethylsilane and 3-methacryloxypropyldimethoxymethylsilane; acrylic silane-based compounds such as 3-acryloxypropyltrimethoxysilane and 3-acryloxypropyltriethoxysilane; isocyanate silane-based compounds such as 3-isocyanatepropyltrimethoxysilane and 3-isocyanatepropyltriethoxysilane; isocyanurate silane-based compounds such as tris-(trimethoxysilylpropyl)isocyanurate; mercaptosilane-based compounds such as 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyldimethoxymethylsilane; ureidosilane-based compounds such as 3-ureidopropyltriethoxysilane; styrylsilane-based compounds such as p-styryltrimethoxysilane; cationic silane-based compounds such as N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane hydrochlorides; acid anhydride-based compounds such as [3-(trimethoxysilyl)propyl]succinic anhydride; phenylsilane-based compounds such as phenyltrimethoxysilane, phenyltriethoxysilane, dimethoxymethylphenylsilane, diethoxymethylphenylsilane and p-tolyltrimethoxysilane; and arylsilane-based compounds such as trimethoxy(l-naphthyl)silane. One of these silane coupling agents can be used, or two or more thereof can be appropriately mixed and used.

In the resin composition, the content of the silane coupling agent is normally 0.1 to 10 parts by mass based on 100 parts by mass of the total of the bismaleimide compound (A) and the maleimide compounds (B).

The wetting and dispersing agent is not particularly limited as long as it is a dispersion stabilizer used for a paint. Specific examples of the wetting and dispersing agent include DISPERBYK (registered trademark)-110 (product name), 111 (product name), 118 (product name), 180 (product name), and 161 (product name), and BYK (registered trademark)-W996 (product name), W9010 (product name), and W903 (product name) manufactured by BYK Japan KK. One of these wetting and dispersing agents can be used, or two or more thereof can be appropriately mixed and used.

In the resin composition, the content of the wetting and dispersing agent is normally 0.1 to 10 parts by mass based on 100 parts by mass of the total of the bismaleimide compound (A) and the maleimide compounds (B).

<Cyanate Compound, Phenolic Resin, Oxetane Resin, Benzoxazine Compound, Epoxy Resin, and Additional Compound>

In the present embodiment, as long as the effect of the present invention is achieved, a variety of types of compounds and resins such as a cyanate compound, a phenolic resin, an oxetane resin, a benzoxazine compound, an epoxy resin and additional compounds in addition to the bismaleimide compound (A), the maleimide compounds (B), the photo initiator (C), the compound (D) containing one or more carboxy groups, and the maleimide compound (E) can be used, depending on characteristics such as flame retardancy, heat resistance and a thermal expansion property of the cured product. Preferably, these compounds and resins ensure that the resin composition becomes light-sensitive to be photocured when exposed with an active energy ray including a wavelength of 365 nm (i-line) and/or an active energy ray including a wavelength of 405 nm (h-line).

One of these compounds and resins can be used, or two or more thereof can be appropriately mixed and used.

<Cyanate Compound>

The cyanate compound is not particularly limited as long as it is a resin having in the molecule an aromatic moiety substituted by at least one cyanate group (cyanate group).

For example, mention may be made of those represented by the formula (26).

In the formula (26), Ar₁ represents a benzene ring, a naphthalene ring, or two benzene rings bonded to each other by a single bond. When there are a plurality of Ar₁, Ar₁ may be the same as or different from each other. Each Ra independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, and a group in which an alkyl group having 1 to 6 carbon atoms and an aryl group having 6 to 12 carbon atoms are bonded to each other. The aromatic ring for Ra may have a substituent, and any position can be selected for the substituents in Ar₁ and Ra. p represents the number of cyanate groups bonded to Ar₁ and each p is independently an integer of 1 to 3. q represents the number of Ra bonded to Ar₁ and is 4−p when Ar₁ is a benzene ring, 6−p when Ar₁ is a naphthalene ring, and 8−p when Ar₁ is two benzene rings bonded to each other by a single bond. t represents the average number of repetitions and is an integer of 0 to 50, and the cyanate compound may be a mixture of compounds having different t. X represents any of a single bond, a divalent organic group having 1 to 50 carbon atoms (a hydrogen atom may be replaced by a heteroatom), a divalent organic group having 1 to 10 nitrogen atoms (for example, —N—R—N— (wherein R represents an organic group)), a carbonyl group (—CO—), a carboxy group (—C(═O)O—), a carbonyl dioxide group (—OC(═O)O—), a sulfonyl group (—SO₂—), a divalent sulfur atom, and a divalent oxygen atom, and X is each independently as defined above when there are a plurality of X.

The alkyl group for Ra in the formula (26) may have either a linear or branched chain structure or a cyclic structure (for example, a cycloalkyl group).

In addition, a hydrogen atom in the alkyl group and the aryl group for Ra in the formula (26) may be replaced by a halogen atom such as a fluorine atom and a chlorine atom; an alkoxyl group such as a methoxy group and a phenoxy group; a cyano group, or the like.

Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a tert-butyl group, a n-pentyl group, a 1-ethylpropyl group, a 2,2-dimethylpropyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, and a trifluoromethyl group.

Specific examples of the alkenyl group include a vinyl group, a (meth)allyl group, an isopropenyl group, a 1-propenyl group, a 2-butenyl group, a 3-butenyl group, a 1,3-butanedienyl group, 2-methyl-2-propenyl group, a 2-pentenyl group, and a 2-hexenyl group.

Specific examples of the aryl group include a phenyl group, a xylyl group, a mesityl group, a naphthyl group, a phenoxyphenyl group, an ethylphenyl group, an o-, m-, or p-fluorophenyl group, a dichlorophenyl group, a dicyanophenyl group, a trifluorophenyl group, a methoxyphenyl group, and an o-, m-, or p-tolyl group.

Examples of the alkoxyl group include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a n-butoxy group, an isobutoxy group, and a tert-butoxy group.

Specific examples of the divalent organic group having 1 to 50 carbon atoms for X in the formula (26) include a methylene group, an ethylene group, a trimethylene group, a cyclopentylene group, a cyclohexylene group, a trimethylcyclohexylene group, a biphenylylmethylene group, a dimethylmethylene-phenylene-dimethylmethylene group, a fluorenediyl group, and a phthalidediyl group. A hydrogen atom in the divalent organic group may be replaced by a halogen atom such as a fluorine atom and a chlorine atom; an alkoxyl group such as a methoxy group and a phenoxy group; a cyano group, or the like.

Examples of the divalent organic group having 1 to 10 nitrogen atoms for X in the formula (26) include an imino group and a polyimide group.

In addition, examples of the organic group of X in the formula (26) include one having a structure represented by the formula (27) or one having a structure represented by the formula (28).

In the formula (27), Ar₂ represents a benzenediyl group, a naphthalenediyl group, or a biphenyldiyl group, and may be the same as or different from each other when u is an integer of 2 or more. Each of Rb, Rc, Rf, and Rg independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, a trifluoromethyl group, or an aryl group having at least one phenolic hydroxy group. Each of Rd and Re is independently selected from any one of a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, and a hydroxy group. u represents an integer of 0 to 5.

In the formula (28), Ar₃ represents a benzenediyl group, a naphthalenediyl group, or a biphenyldiyl group, and may be the same as or different from each other when v is an integer of 2 or more. Each of Ri and Rj independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, a benzyl group, an alkoxyl group having 1 to 4 carbon atoms, a hydroxy group, a trifluoromethyl group, or an aryl group substituted by at least one cyanate group. v represents an integer of 0 to 5, and the cyanate compound may be a mixture of compounds having different v.

Furthermore, examples of X in the formula (26) include divalent groups represented by the following formulas.

Here, in the above formula, z represents an integer of 4 to 7. Each Rk independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

Specific examples of Ar₂ in the formula (27) and Ar₃ in the formula (28) include a benzenediyl group to which two carbon atoms shown in the formula (27) or two oxygen atoms shown in the formula (28) are bonded at positions 1 and 4 or positions 1 and 3, a biphenyldiyl group to which the above two carbon atoms or two oxygen atoms are bonded at positions 4 and 4′, positions 2 and 4′, positions 2 and 2′, positions 2 and 3′, positions 3 and 3′, or positions 3 and 4′, and a naphthalenediyl group to which the above two carbon atoms or two oxygen atoms are bonded at positions 2 and 6, positions 1 and 5, positions 1 and 6, positions 1 and 8, positions 1 and 3, positions 1 and 4, or positions 2 and 7.

The alkyl group and the aryl group for Rb, Rc, Rd, Re, Rf, and Rg in the formula (27) and Ri and Rj in the formula (28) have the same meanings as those in the above formula (26).

Specific examples of the cyanate-substituted aromatic compound represented by the above formula (26) include cyanatebenzene, 1-cyanate-2-, 1-cyanate-3-, or 1-cyanate-4-methylbenzene, 1-cyanate-2-, 1-cyanate-3-, or 1-cyanate-4-methoxybenzene, 1-cyanate-2,3-, 1-cyanate-2,4-, 1-cyanate-2,5-, 1-cyanate-2,6-, 1-cyanate-3,4-, or 1-cyanate-3,5-dimethylbenzene, cyanateethylbenzene, cyanatebutylbenzene, cyanateoctylbenzene, cyanatenonylbenzene, 2-(4-cyanatephenyl)-2-phenylpropane (a cyanate of 4-α-cumylphenol), 1-cyanate cyclohexylbenzene, 1-cyanate-4-vinylbenzene, 1-cyanate or 1-cyanate-3-chlorobenzene, 1-cyanate-2,6-dichlorobenzene, 1-cyanate-2-methyl-3-chlorobenzene, cyanatenitrobenzene, 1-cyanate-4-nitro-2-ethylbenzene, 1-cyanate-2-methoxy-4-allylbenzene (a cyanate of eugenol), methyl(4-cyanatephenyl)sulfide, 1-cyanate trifluoromethylbenzene, 4-cyanatebiphenyl, 1-cyanate or 1-cyanate-4-acetylbenzene, 4-cyanatebenzaldehyde, methyl 4-cyanatebenzoate ester, phenyl 4-cyanatebenzoate ester, 1-cyanate-4-acetaminobenzene, 4-cyanatebenzophenone, 1-cyanate-2,6-di-tert-butylbenzene, 1,2-dicyanatebenzene, 1,3-dicyanatebenzene, 1,4-dicyanatebenzene, 1,4-dicyanate-2-tert-butylbenzene, 1,4-dicyanate-2,4-dimethylbenzene, 1,4-dicyanate-2,3,4-dimethylbenzene, 1,3-dicyanate-2,4,6-trimethylbenzene, 1,3-dicyanate-5-methylbenzene, 1-cyanate- or 2-cyanatenaphthalene, 1-cyanate-4-methoxynaphthalene, 2-cyanate-6-methoxynaphthalene, 2-cyanate-7-methoxynaphthalene, 2,2′-dicyanate-1,1′-binaphthyl, 1,3-, 1,4-, 1,5-, 1,6-, 1,7-, 2,3-, 2,6-, or 2,7-dicyanatenaphthalene, 2,2′- or 4,4′-dicyanatebiphenyl, 4,4′-dicyanateoctafluorobiphenyl, 2,4′- or 4,4′-dicyanatediphenylmethane, bis(4-cyanate-3,5-dimethylphenyl)methane, 1,1-bis(4-cyanatephenyl)ethane, 1,1-bis(4-cyanatephenyl)propane, 2,2-bis(4-cyanatephenyl)propane, 2,2-bis(4-cyanate-3-methylphenyl)propane, 2,2-bis(2-cyanate biphenylyl)propane, 2,2-bis(4-cyanatephenyl)hexafluoropropane, 2,2-bis(4-cyanate-3,5-dimethylphenyl)propane, 1,1-bis(4-cyanatephenyl)butane, 1,1-bis(4-cyanatephenyl)isobutane, 1,1-bis(4-cyanatephenyl)pentane, 1,1-bis(4-cyanatephenyl)-3-methylbutane, 1,1-bis(4-cyanatephenyl)-2-methylbutane, 1,1-bis(4-cyanatephenyl)-2,2-dimethylpropane, 2,2-bis(4-cyanatephenyl)butane, 2,2-bis(4-cyanatephenyl)pentane, 2,2-bis(4-cyanatephenyl)hexane, 2,2-bis(4-cyanatephenyl)-3-methylbutane, 2,2-bis(4-cyanatephenyl)-4-methylpentane, 2,2-bis(4-cyanatephenyl)-3,3-dimethylbutane, 3,3-bis(4-cyanatephenyl)hexane, 3,3-bis(4-cyanatephenyl)heptane, 3,3-bis(4-cyanatephenyl)octane, 3,3-bis(4-cyanatephenyl)-2-methylpentane, 3,3-bis(4-cyanatephenyl)-2-methylhexane, 3,3-bis(4-cyanatephenyl)-2,2-dimethylpentane, 4,4-bis(4-cyanatephenyl)-3-methylheptane, 3,3-bis(4-cyanatephenyl)-2-methylheptane, 3,3-bis(4-cyanatephenyl)-2,2-dimethylhexane, 3,3-bis(4-cyanatephenyl)-2,4-dimethylhexane, 3,3-bis(4-cyanatephenyl)-2,2,4-trimethylpentane, 2,2-bis(4-cyanatephenyl)-1,1,1,3,3,3-hexafluoropropane, bis(4-cyanatephenyl)phenylmethane, 1,1-bis(4-cyanatephenyl)-1-phenylethane, bis(4-cyanatephenyl)biphenylmethane, 1,1-bis(4-cyanatephenyl)cyclopentane, 1,1-bis(4-cyanatephenyl)cyclohexane, 2,2-bis(4-cyanate-3-isopropylphenyl)propane, 1,1-bis(3-cyclohexyl-4-cyanatephenyl)cyclohexane, bis(4-cyanatephenyl)diphenylmethane, bis(4-cyanatephenyl)-2,2-dichloroethylene, 1,3-bis[2-(4-cyanatephenyl) propyl]benzene, 1,4-bis[2-(4-cyanatephenyl) propyl]benzene, 1,1-bis(4-cyanatephenyl)-3,3,5-trimethylcyclohexane, 4-[bis(4-cyanatephenyl)methyl]biphenyl, 4,4-dicyanatebenzophenone, 1,3-bis(4-cyanatephenyl)-2-propen-1-one, bis(4-cyanatephenyl) ether, bis(4-cyanatephenyl) sulfide, bis(4-cyanatephenyl) sulfone, 4-cyanatebenzoic acid-4-cyanatephenyl ester (4-cyanatephenyl-4-cyanatebenzoate), bis-(4-cyanatephenyl) carbonate, 1,3-bis(4-cyanatephenyl)adamantane, 1,3-bis(4-cyanatephenyl)-5,7-dimethyladamantane, 3,3-bis(4-cyanatephenyl)isobenzofuran-1(3H)-one (a cyanate of phenolphthalein), 3,3-bis(4-cyanate-3-methylphenyl)isobenzofuran-1(3H)-one (a cyanate of o-cresolphthalein), 9,9′-bis(4-cyanatephenyl)fluorene, 9,9-bis(4-cyanate-3-methylphenyl)fluorene, 9,9-bis(2-cyanate-5-biphenylyl)fluorene, tris(4-cyanatephenyl)methane, 1,1,1-tris(4-cyanatephenyl)ethane, 1,1,3-tris(4-cyanatephenyl)propane, α,α,α′-tris(4-cyanatephenyl)-1-ethyl-4-isopropylbenzene, 1,1,2,2-tetrakis(4-cyanatephenyl)ethane, tetrakis(4-cyanatephenyl)methane, 2,4,6-tris(N-methyl-4-cyanateanilino)-1,3,5-triazine, 2,4-bis(N-methyl-4-cyanateanilino)-6-(N-methylanilino)-1,3,5-triazine, bis(N-4-cyanate-2-methylphenyl)-4,4′-oxydiphthalimide, bis(N-3-cyanate-4-methylphenyl)-4,4′-oxydiphthalimide, bis(N-4-cyanatephenyl)-4,4′-oxydiphthalimide, bis(N-4-cyanate-2-methylphenyl)-4,4′-(hexafluoroisopropylidene)diphthalimide, tris(3,5-dimethyl-4-cyanatebenzyl) isocyanurate, 2-phenyl-3,3-bis(4-cyanatephenyl)phthalimidine, 2-(4-methylphenyl)-3,3-bis(4-cyanatephenyl)phthalimidine, 2-phenyl-3,3-bis(4-cyanate-3-methylphenyl)phthalimidine, 1-methyl-3,3-bis(4-cyanatephenyl)indolin-2-one, and 2-phenyl-3,3-bis(4-cyanatephenyl)indolin-2-one.

One of these cyanate compounds can be used, or two or more thereof can be appropriately mixed and used.

Other specific examples of the cyanate compound represented by the formula (26) include those obtained by cyanation of a phenolic resin such as a phenol novolac resin and a cresol novolac resin (those obtained by reacting phenol, an alkyl-substituted phenol or a halogen-substituted phenol with a formaldehyde compound such as formalin or paraformaldehyde in an acidic solution, using a publicly known method), a trisphenol novolac resin (those obtained by reacting hydroxybenzaldehyde with phenol in the presence of an acidic catalyst), a fluorene novolac resin (those obtained by reacting a fluorenone compound with a 9,9-bis(hydroxyaryl)fluorene in the presence of an acidic catalyst), a phenol aralkyl resin, a cresol aralkyl resin, a naphthol aralkyl resin, and a biphenyl aralkyl resin (those obtained by reacting a bishalogenomethyl compound as represented by Ar₄—(CH₂Y)₂ (wherein Ar₄ represents a phenyl group and Y represents a halogen atom. The same applies in this paragraph) with a phenolic compound with an acidic catalyst or with no catalyst, those obtained by reacting a bis(alkoxymethyl) compound as represented by Ar₄—(CH₂OR)₂ (wherein R represents an alkyl group) with a phenolic compound in the presence of an acidic catalyst, or those obtained by reacting a bis(hydroxymethyl) compound as represented by Ar₄—(CH₂OH)₂ with a phenolic compound in the presence of an acidic catalyst, or those obtained by polycondensing an aromatic aldehyde compound, an aralkyl compound, and a phenolic compound, using a publicly known method), a phenol-modified xylene formaldehyde resin (those obtained by reacting a xylene formaldehyde resin with a phenolic compound in the presence of an acidic catalyst, using a publicly known method), a modified naphthalene formaldehyde resin (those obtained by reacting a naphthalene formaldehyde resin with a hydroxy-substituted aromatic compound in the presence of an acidic catalyst, using a publicly known method), a phenol-modified dicyclopentadiene resin, or a phenolic resin having a polynaphthylene ether structure (those obtained by subjecting a polyvalent hydroxynaphthalene compound having two or more phenolic hydroxy groups in one molecule to dehydration condensation in the presence of a basic catalyst, using a publicly known method) by a method similar to the above, and a prepolymer thereof. One of these cyanate compounds can be used, or two or more thereof can be appropriately mixed and used.

The method for producing these cyanate compounds is not particularly limited, and a publicly known method can be used. Specific examples thereof include acquisition or synthesis of a hydroxy group containing compound having a desired backbone and cyanation of that compound by modifying the hydroxy group by a publicly known method. Examples of the approach for the cyanation of hydroxy groups include, for example, the approach described in Ian Hamerton, “Chemistry and Technology of Cyanate Ester Resins, “Blackie Academic & Professional.

The cured product using these cyanate compounds has characteristics of being excellent in glass transition temperature, a low thermal expansion property, plating adhesiveness, and the like.

In the resin composition, the content of the cyanate compound is normally 0.01 to 40 parts by mass based on 100 parts by mass of the total of the bismaleimide compound (A) and the maleimide compounds (B).

<Phenolic Resin>

As the phenolic resin, those publicly known in general can be used as long as they are phenolic resins having two or more hydroxyl groups in one molecule. Examples thereof include a bisphenol A-based phenolic resin, a bisphenol E-based phenolic resin, a bisphenol F-based phenolic resin, a bisphenol S-based phenolic resin, a phenol novolac resin, a bisphenol A novolac-based phenolic resin, a glycidyl ester-based phenolic resin, an aralkyl novolac-based phenolic resin, a biphenyl aralkyl-based phenolic resin, a cresol novolac-based phenolic resin, a polyfunctional phenolic resin, a naphthol resin, a naphthol novolac resin, a polyfunctional naphthol resin, an anthracene-based phenolic resin, a naphthalene backbone modified novolac-based phenolic resin, a phenol aralkyl-based phenolic resin, a naphthol aralkyl-based phenolic resin, a dicyclopentadiene-based phenolic resin, a biphenyl-based phenolic resin, an alicyclic phenolic resin, a polyol-based phenolic resin, a phosphorus containing phenolic resin, a polymerizable unsaturated hydrocarbon group containing phenolic resin, and a hydroxyl group containing silicone resin. One of these phenol resins can be used, or two or more thereof can be appropriately mixed and used.

In the resin composition, the content of the phenolic resin is normally 0.01 to 40 parts by mass based on 100 parts by mass of the total of the bismaleimide compound (A) and the maleimide compounds (B).

<Oxetane Resin>

As the oxetane resin, those publicly known in general can be used. Examples thereof include, for example, oxetane, an alkyloxetane such as 2-methyloxetane, 2,2-dimethyloxetane, 3-methyloxetane, and 3,3-dimethyloxetane, 3-methyl-3-methoxymethyloxetane, 3,3-di(trifluoromethyl)perfluorooxetane, 2-chloromethyloxetane, 3,3-bis(chloromethyl)oxetane, biphenyl-based oxetane, OXT-101 (manufactured by Toagosei Co., Ltd., product name), OXT-121 (manufactured by Toagosei Co., Ltd., product name), and OXT-221 (manufactured by Toagosei Co., Ltd., product name). One of these oxetane resins can be used, or two or more thereof can be appropriately mixed and used.

In the resin composition, the content of the oxetane resin is normally 0.01 to 40 parts by mass based on 100 parts by mass of the total of the bismaleimide compound (A) and the maleimide compounds (B).

<Benzoxazine Compound>

As the benzoxazine compound, those publicly known in general can be used as long as they are compounds having two or more dihydrobenzoxazine rings in one molecule. Examples thereof include a bisphenol A-based benzoxazine BA-BXZ (manufactured by Konishi Chemical Ind. Co., Ltd., product name), a bisphenol F-based benzoxazine BF-BXZ (manufactured by Konishi Chemical Ind. Co., Ltd., product name), a bisphenol S-based benzoxazine BS-BXZ (manufactured by Konishi Chemical Ind. Co., Ltd., product name), and a phenolphthalein-based benzoxazine. One of these benzoxazine compounds can be used, or two or more thereof can be appropriately mixed and used.

In the resin composition, the content of the benzoxazine compound is normally 0.01 to 40 parts by mass based on 100 parts by mass of the total of the bismaleimide compound (A) and the maleimide compounds (B).

<Epoxy Resin>

There is no particular limitation on the epoxy resin, and those publicly known in general can be used. Examples thereof include, for example, a bisphenol A-based epoxy resin, a bisphenol E-based epoxy resin, a bisphenol F-based epoxy resin, a bisphenol S-based epoxy resin, a bisphenol A novolac-based epoxy resin, a biphenyl-based epoxy resin, a phenol novolac-based epoxy resin, a cresol novolac-based epoxy resin, a xylene novolac-based epoxy resin, a polyfunctional phenol-based epoxy resin, a naphthalene-based epoxy resin, a naphthalene backbone modified novolac-based epoxy resin, a naphthylene ether-based epoxy resin, a phenol aralkyl-based epoxy resin, an anthracene-based epoxy resin, a trifunctional phenol-based epoxy resin, a tetrafunctional phenol-based epoxy resin, triglycidyl isocyanurate, a glycidyl ester-based epoxy resin, an alicyclic epoxy resin, a dicyclopentadiene novolac-based epoxy resin, a biphenyl novolac-based epoxy resin, a phenol aralkyl novolac-based epoxy resin, a naphthol aralkyl novolac-based epoxy resin, an aralkyl novolac-based epoxy resin, a naphthol aralkyl-based epoxy resin, a dicyclopentadiene-based epoxy resin, a polyol-based epoxy resin, a phosphorus containing epoxy resin, a glycidyl amine, a compound obtained by epoxidizing a double bond of butadiene and the like, a compound obtained by the reaction between a hydroxyl group containing silicone resin and epichlorohydrin, and a halide thereof. One of these epoxy resins can be used, or two or more thereof can be appropriately mixed and used.

As the epoxy resin, commercial products can be used, and examples thereof include an epoxy resin represented by the formula (29) (NC-3000FH (product name) manufactured by Nippon Kayaku Co., Ltd., n₅ is about 4 in the formula (29)), and a naphthalene-based epoxy resin represented by the formula (30) (HP-4710 (product name) manufactured by DIC CORPORATION).

One of these epoxy resins can be used, or two or more thereof can be appropriately mixed and used.

In the resin composition, the content of the epoxy resin is normally 0.01 to 40 parts by mass based on 100 parts by mass of the total of the bismaleimide compound (A) and the maleimide compounds (B).

<Additional Compound>

Examples of the additional compound include a vinyl ether such as ethyl vinyl ether, propyl vinyl ether, hydroxyethyl vinyl ether, and ethylene glycol divinyl ether; a styrene such as styrene, methylstyrene, ethylstyrene, and divinylbenzene; triallyl isocyanurate, trimethallyl isocyanurate, and bisallylnadic imide. One of these compounds can be used, or two or more thereof can be appropriately mixed and used.

In the resin composition, the content of the additional compound is normally 0.01 to 40 parts by mass based on 100 parts by mass of the total of the bismaleimide compound (A) and the maleimide compounds (B).

<Organic Solvent>

The resin composition of the present embodiment may contain an organic solvent if required. When an organic solvent is used, the viscosity can be adjusted during the preparation of the resin composition. The type of the organic solvent is not particularly limited as long as it is capable of dissolving a part of or all of the resin in the resin composition.

Examples of such an organic solvent include halogen solvents such as dichloromethane, chloroform, dichloroethane, and chlorobenzene; aprotic polar solvents such as dimethylformamide, dimethylacetamide, dimethylsulfoxide, tetrahydrofuran, dioxane, and acetonitrile; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl keton, cyclopentanone, and cyclohexanone; cellosolve solvents such as 2-ethoxyethanol and propylene glycol monomethyl ether; aliphatic alcohol solvents such as methanol, ethanol, propanol, isopropanol, and butanol; aromatic group-containing phenol solvents such as phenol and cresol;

ester solvents such as ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, isoamyl acetate, methyl methoxypropionate, methyl hydroxyisobutyrate, γ-butyrolactone, and propylene glycol monomethyl ether acetate; aromatic hydrocarbon solvents such as toluene and xylene.

Among the above, methyl ethyl ketone, propylene glycol monomethyl ether acetate, and dimethylacetamide are preferable because the solvent can exhibit excellent solubility in the bismaleimide compound (A) and the maleimide compounds (B), and furthermore, also in other resins and compounds such as the photo initiator (C) and the compound (D) containing one or more carboxyl groups, and therefore a varnish having good solubility is easily prepared. One of these organic solvents can be used, or two or more thereof can be appropriately mixed and used.

<Additional Component>

In the resin composition of the present embodiment, a variety of polymer compounds such as thermosetting resins, thermoplastic resins and oligomers thereof, and elastomers, which have not been mentioned before; flame retardant compounds, which have not been mentioned before; additive agents and the like can also be used in combination to the extent that the characteristics of the present embodiment are not impaired. These are not particularly limited as long as they are those generally used. Examples of the flame retardant compound include, for example, a nitrogen containing compound such as melamine and benzoguanamine; an oxazine ring containing compound; and a phosphorus compound such as a phosphate compound, an aromatic fused phosphate ester, and a halogen containing fused phosphate ester. Examples of the additive agent include, for example, an ultraviolet absorbing agent, an antioxidant, a fluorescent brightening agent, a photosensitizer, a dye, a pigment, a thickening agent, a lubricant, a defoaming agent, a surface conditioner, a brightening agent, a polymerization inhibitor, and a thermal curing accelerator. One of these components can be used, or two or more thereof can be appropriately mixed and used.

In the resin composition, the content of the additional component is normally 0.1 to 10 parts by mass based on 100 parts by mass of the total of the bismaleimide compound (A) and the maleimide compounds (B).

<Method for Producing Resin Composition and Varnish>

The resin composition of the present embodiment can be prepared by appropriately mixing the bismaleimide compound (A), the maleimide compounds (B), and if required, the photo initiator (C), the compound (D) containing one or more carboxy groups, the maleimide compound (E), the filler (F), the additional resin, the additional compound, the additive, and the like. Examples of the method for producing the resin composition include a method in which each of the components described above is sequentially compounded in a solvent and stirred sufficiently. The resin composition of the present embodiment at least contains the bismaleimide compound (A) and the maleimide compounds (B) and has good solubility in an organic solvent. In addition, the resin composition also has excellent photocurability and excellent alkaline-developability by further containing the photo initiator and the compound containing one or more carboxyl groups. Thus, the varnish obtained from the resin composition has moderate viscosity and the amount of liquid components is small in the varnish, and thus the resin sheet obtained by drying the varnish has satisfactorily suppressed tackiness while having good photocurability and alkaline-developability. The organic solvent used for preparation of varnish is not particularly limited, and specific examples thereof are as described above.

Upon producing the resin composition, publicly known treatment (stirring, mixing, and kneading treatment and the like) for uniformly dissolving or dispersing each component can be carried out, if required. Specifically, by using a stirring tank equipped with a stirrer having an appropriate stirring capacity to carry out the stirring and dispersion treatment, the dispersibility of each component such as the bismaleimide compound (A) and the maleimide compounds (B) in the resin composition can be improved. The stirring, mixing, and kneading treatment can be appropriately carried out by using a publicly known apparatus such as a stirring apparatus intended for dispersion such as an ultrasonic homogenizer; an apparatus intended for mixing such as a three roll mill, a ball mill, a bead mill, or a sand mill; or a revolution or rotation mixing apparatus. In addition, upon preparing the resin composition, an organic solvent can be used if required. The type of the organic solvent is not particularly limited as long as it is capable of dissolving the resin in the resin composition, and specific examples thereof are as described above.

The resin composition can be suitably used as a varnish upon fabricating a resin sheet of the present embodiment, which will be mentioned later. The varnish can be obtained by a publicly known method. For example, the varnish can be obtained by adding 10 to 900 parts by mass, preferably 30 to 500 parts by mass of an organic solvent to 100 parts by mass of components other than the organic solvent in the resin composition and carrying out the publicly known mixing treatment (stirring, kneading treatment or the like). In the present embodiment, since the resin composition can dissolve in an organic solvent satisfactorily and a varnish having moderate viscosity can be prepared, the mixing treatment is preferably carried out at a temperature of 30 to 120° C., and more preferably at a temperature of 40 to 100° C. The time of the mixing treatment is normally 1 to 30 minutes.

[Application]

The resin composition of the present embodiment can be used in applications where an insulation resin composition is required, and the applications are not particularly limited. For example, the resin composition of the present embodiment can be used for a photosensitive film, a photosensitive film with a support, a prepreg, a resin sheet, a circuit substrate (applications for a laminate, applications for a multilayer printed wiring board, and the like), a solder resist, an underfill material, a die bonding material, a semiconductor sealing material, a hole filling resin, a component embedding resin, and the like. Among the above, the resin composition can be suitably used for insulation layers of multilayer printed wiring boards or solder resists because the resin composition has excellent solubility, photocurability, and alkaline-developability, and tackiness is suitably suppressed when used for resin sheets and printed wiring boards.

[Cured Product]

The cured product can be obtained by curing the resin composition. The cured product can be obtained by, for example, melting the resin composition or dissolving the resin composition in a solvent, then pouring the resin composition into a mold, and curing the resin composition with light under normal conditions. It is preferable to cure the resin composition in a light wavelength range of 100 to 500 nm where curing is efficiently promoted by a photo initiator or the like.

[Resin Sheet]

A resin sheet of the present embodiment is a resin sheet with a support containing: a support; and a resin layer disposed on one surface or both surfaces of the support, wherein the resin layer contains the resin composition of the present embodiment. The resin sheet can be produced by applying the resin composition onto the support and drying the resultant. The resin layer in the resin sheet has satisfactorily suppressed tackiness, and excellent photocurability and alkaline developability.

As the support, those publicly known can be used and there is no particular limitation thereon, but it is preferably a resin film. Examples of the resin film include, for example, a polyimide film, a polyamide film, a polyester film, a polyethylene terephthalate (PET) film, a polybutylene terephthalate (PBT) film, a polypropylene (PP) film, a polyethylene (PE) film, a polyethylene naphthalate film, a polyvinyl alcohol film, and a triacetyl acetate film. Among the above, a PET film is preferable.

Preferably, the surface of the resin film is coated with a release agent in order to facilitate release from the resin layer. The thickness of the resin film is preferably in the range of 5 to 100 μm and more preferably in the range of 10 to 50 μm. When the thickness is less than 5 μm, the support tends to be easily torn at the time when the support is released before alkaline development, and when the thickness is greater than 100 μm, the resolution upon being exposed through the support tends to be reduced.

In addition, in order to reduce light scattering during exposure, it is preferable that the resin film should have excellent transparency.

Furthermore, in the resin sheet, the resin layer thereof may be protected with a protective film.

By protecting the resin layer side with a protective film, adhesion of dust and the like to the surface of the resin layer and scratches can be prevented. In addition, since the resin layer has satisfactorily suppressed tackiness while having photocurability and alkaline-developability, the protective film can be easily peeled off after curing of the resin layer. As the protective film, a film composed of a material similar to the resin film can be used. The thickness of the protective film is preferably in the range of 1 to 50 μm and more preferably in the range of 5 to 40 μm. If the thickness is less than 1 μm, the handleability of the protective film tends to be reduced, and if the thickness is greater than 50 μm, the inexpensiveness tends to be poor. Note that it is preferable for the protective film to have a smaller adhesive force between the resin layer and the protective film than the adhesive force between the resin layer and the support.

Examples of the method for producing the resin sheet include a method in which the resin composition is applied to a support such as PET film and the organic solvent is removed by drying to produce the resin sheet.

The application method can be carried out by a publicly known method using, for example, a roll coater, a comma coater, a gravure coater, a die coater, a bar coater, a lip coater, a knife coater, a squeeze coater, or the like. The drying can be carried out by, for example, a method of heating in a dryer at 60 to 200° C. for 1 to 60 minutes.

The amount of organic solvent remaining in the resin layer is preferably 5% by mass or less based on the total mass of the resin layer from the viewpoint of preventing diffusion of the organic solvent in the subsequent steps. It is preferable that the thickness of the resin layer should be 1 to 50 μm from the viewpoint of improving handleability.

The resin sheet can be used for production of insulation layers of multilayer printed wiring boards.

[Multilayer Printed Wiring Board]

The multilayer printed wiring board in the present embodiment contains an insulation layer; and a conductor layer formed on one surface or both surfaces of the insulation layer, wherein the insulation layer contains the resin composition of the present embodiment. The insulation layer can also be obtained by, for example, laminating one or more of the resin sheets and curing them. For the number of laminations in the insulation layer and the conductor layer, the number of laminations can be appropriately set according to an intended application. The order of the insulation layer and the conductor layer is not particularly limited. The conductor layer may be a metal foil used for various printed wiring board materials, and examples thereof include metal foils of copper, aluminum and the like. Examples of the copper metal foil include a rolled copper foil and an electrolytic copper foil. The thickness of the conductor layer is normally 1 to 100 μm. In particular, it can be produced by the following method.

(Lamination Step)

In a lamination step, the resin layer side of the resin sheet is laminated to one surface or both surfaces of a circuit substrate using a vacuum laminator. Examples of the circuit substrate include, for example, a glass epoxy substrate, a metal substrate, a ceramic substrate, a silicon substrate, a semiconductor sealing resin substrate, a polyester substrate, a polyimide substrate, a BT resin substrate, and a thermosetting polyphenylene ether substrate. Note that a circuit substrate refers to a substrate in which a patterned conductor layer (circuit) is formed on one surface or both surfaces of a substrate as described above. Also, in a multilayer printed wiring board formed by alternately laminating a conductor layer and an insulation layer, a substrate in which one surface or both surfaces of the outermost layer of the multilayer printed wiring board are patterned conductor layers (circuits) is also included in the circuit substrate. Note that the insulation layer laminated on the multilayer printed wiring board may be an insulation layer obtained by laminating and curing one or more resin sheets of the present embodiment, or an insulation layer obtained by laminating one or more resin sheets of the present embodiment and one or more publicly known resin sheets different from the resin sheet of the present embodiment. Note that the mode in which the resin sheets of the present embodiment and the publicly known resin sheets different from the resin sheet of the present embodiment are laminated is not particularly limited. The surface of the conductor layer may be subjected to blackening treatment and/or roughening treatment by copper etching or the like in advance. In the lamination step, when the resin sheet has a protective film, the protective film is peeled off and removed. Then, the resin sheet and the circuit substrate are preheated if required, and while pressurizing and heating the resin layer of the resin sheet, it is crimped to the circuit substrate. In the present embodiment, a method of laminating the resin layer of the resin sheet to the circuit substrate under reduced pressure using a vacuum lamination method is suitably used.

As conditions of the lamination step, for example, it is preferable to perform the lamination under reduced pressure with a crimping temperature (lamination temperature) of 50 to 140° C., crimping pressure of 1 to 15 kgf/cm², crimping time of 5 to 300 seconds, and air pressure of 20 mmHg or less. Also, the lamination step may be in a batch type or in a continuous type using a roll. The vacuum lamination method can be carried out using a commercially available vacuum laminator. Examples of the commercially available vacuum laminator include, for example, a two-stage build-up laminator manufactured by Nikko-Materials Co., Ltd.

(Exposure Step)

In the exposure step, after providing the resin layer on the circuit substrate by the lamination step, a predetermined portion of the resin layer is irradiated with an active energy ray as a light source to cure the resin layer in the irradiated part. The tackiness of the obtained resin layer is suitably suppressed. The compound (D) does not hinder photocuring reaction in the exposure step.

The irradiation may be performed through a mask pattern or may be performed by using the direct imaging method in which the irradiation is directly applied. Examples of the active energy ray include, for example, ultraviolet rays, visible rays of light, electron beam, and X-rays. The wavelength of the active energy ray is, for example, in the range of 200 to 600 nm. When an ultraviolet ray is used, the irradiation amount thereof is approximately 10 to 1000 mJ/cm². Upon producing a printed wiring board having a highly dense and highly detailed wiring formation (pattern) using the stepper exposure method, it is preferable to use, for example, an active energy ray including a wavelength of 365 nm (i-line) as an active energy ray. When an active energy ray including a wavelength of 365 nm (i-line) is used, the irradiation amount is approximately 10 to 10,000 mJ/cm². Upon producing a printed wiring board having a highly dense and highly detailed wiring formation (pattern) using the direct imaging method, it is preferable to use, for example, an active energy ray including a wavelength of 405 nm (h-line) as an active energy ray. When an active energy ray including a wavelength of 405 nm (h-line) is used, the irradiation amount is approximately 10 to 10,000 mJ/cm².

There are two exposure methods for passing through the mask pattern: the contact exposure method, in which the mask pattern is adhered to the multilayer printed wiring board, and the non-contact exposure method, in which parallel light rays are used to perform the exposure without adhering the mask pattern to the multilayer printed wiring board, but either method may be used. Also, when a support is present on the resin layer, it may be exposed from the top of the support, or it may be exposed after the support is removed.

(Alkaline Development Step)

When a support is not present on the resin layer, a portion which is not photocured directly in alkaline development (unexposed portion) is removed after the exposure step, and development is performed, whereby an insulation layer pattern can be formed.

When a support is present on the resin layer, the support is removed after the exposure step, and thereafter a portion which is not photocured in alkaline development (unexposed portion) is removed, and development is performed, whereby an insulation layer pattern can be formed.

The unexposed resin layer containing the resin composition of the present embodiment has excellent alkaline developability, so that it is possible to obtain a printed wiring board having a highly detailed pattern.

In the case of alkaline development, the developing solution is not particularly limited as long as unexposed portion is selectively eluted, and alkaline developing solutions such as an aqueous tetramethylammonium hydroxide solution, an aqueous sodium carbonate solution, an aqueous potassium carbonate solution, an aqueous sodium hydroxide solution and an aqueous potassium hydroxide solution are used. In the present embodiment, it is more preferable to use an aqueous tetramethylammonium hydroxide solution. One of these alkaline developing solutions can be used, or two or more thereof can be appropriately mixed and used.

As the alkaline development method, for example, a known method such as dipping, paddling, spraying, shaking immersion, blushing and scraping can be carried out. In pattern formation, these development methods can be used in combination if necessary. As the development method, use of a high-pressure spray is suitable because the resolution is further improved. When the spraying method is employed, the spray pressure is preferably 0.02 to 0.5 MPa.

(Postbaking Step)

In the present embodiment, a postbaking step is carried out after the alkaline development step, thereby forming an insulation layer (cured product). Examples of the postbaking step include an ultraviolet irradiation step with a high pressure mercury lamp and a heating step using a clean oven, and these steps may be used in combination as well. When irradiating with ultraviolet ray, the irradiation amount thereof can be adjusted if required, and for example, the irradiation can be carried out at an irradiation amount of approximately 0.05 to 10 J/cm². Also, the conditions of heating can be appropriately selected if required, but they are preferably selected from the range of 20 to 180 minutes at 150 to 220° C., and more preferably from the range of 30 to 150 minutes at 160 to 200° C.

(Conductor Layer Formation Step)

After forming the insulation layer (cured product), a conductor layer is formed on the surface of the insulation layer by dry plating.

When the conductor layer is formed, the surface of the insulation layer may be subjected to surface modification treatment before dry plating. As the surface modification treatment, a known method such as plasma etching treatment, reverse sputtering treatment, and corona treatment can be used.

For the dry plating, a publicly known method such as a vapor deposition method, a sputtering method, and an ion plating method can be used. In the vapor deposition method (vacuum deposition method), for example, a metallic film can be formed on the insulation layer by placing the multilayer printed wiring board in a vacuum container and heating and evaporating the metal. In the sputtering method as well, for example, the multilayer printed wiring board is placed in a vacuum container, an inert gas such as argon is introduced, a direct current voltage is applied, the ionized inert gas is brought into collision with the target metal, and the knocked-out metal can be used to form a metallic film on the insulation layer.

Next, a conductor layer is formed by nonelectrolytic plating or electroplating. As a method of subsequent pattern formation, for example, a subtractive method, a semi-additive method, or the like can be used.

[Semiconductor Device]

A semiconductor device of the present embodiment contains the resin composition of the present embodiment. In particular, it can be produced by the following method. A semiconductor device can be produced by a mounting semiconductor chip at the conduction points on the multilayer printed wiring board. Here, the conduction points refer to the points in the multilayer printed wiring board where electrical signals are conveyed, and the locations thereof may be on the surface or at embedded points. In addition, the semiconductor chip is not particularly limited as long as they are electrical circuit elements made of semiconductors.

The method for mounting the semiconductor chip upon producing the semiconductor device is not particularly limited as long as the semiconductor chip effectively functions. Specific examples thereof include a wire bonding mounting method, a flip chip mounting method, a mounting method with a bumpless build-up layer (BBUL), a mounting method with an anisotropic conductive film (ACF), and a mounting method with a non-conductive film (NCF).

Alternatively, the semiconductor device can be produced by forming an insulation layer containing the resin composition on a semiconductor chip or a substrate on which semiconductor chip is mounted. The shape of the substrate on which semiconductor chip is mounted may be wafer-like or panel-like. After the formation, the semiconductor device can be produced using the same method as the multilayer printed wiring board described above.

EXAMPLES

The present embodiment will be more specifically described below using Examples and Comparative Examples. The present embodiment is not limited in any way by the following Examples.

[Evaluation of Raw Material]

[Transmittance and Absorbance]

As the bismaleimide compound (A), MIZ-001 (product name, mass average molecular weight (Mw): 3000) manufactured by Nippon Kayaku Co., Ltd. was used to prepare a chloroform solution containing this MIZ-001 (product name) at 1% by mass, and measurement of the transmittance at each of a wavelength of 365 nm and a wavelength of 405 nm was carried out using an UV-vis measuring apparatus (Hitachi Spectrophotometer U-4100 (product name) manufactured by Hitachi High-Technologies Corporation).

As the photo initiator (C), bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Omnirad (registered trademark) 819 (product name) manufactured by IGM Resins B.V.) was used to prepare a chloroform solution containing this Omnirad (registered trademark) 819 (product name) at 0.01% by mass, and measurement of the absorbance at each of a wavelength of 365 nm and a wavelength of 405 nm was carried out using an UV-vis measuring apparatus (U-4100 (product name)).

In the same manner, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (Omnirad (registered trademark) 369 (product name) manufactured by IGM Resins B.V.) and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (Omnirad (registered trademark) 907 (product name) manufactured by IGM Resins B.V.) were used as the photo initiators, and measurement of the absorbance at each of a wavelength of 365 nm and a wavelength of 405 nm was carried out.

As the compound (D) containing one or more carboxy groups, cis-4-cyclohexene-1,2-dicarboxylic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight: 152) was used to prepare a N-methylpyrrolidone solution containing this cis-4-cyclohexene-1,2-dicarboxylic anhydride (product name) at 1% by mass, and measurement of the transmittance at each of a wavelength of 365 nm and a wavelength of 405 nm was carried out using an UV-vis measuring apparatus (Hitachi Spectrophotometer U-4100 manufactured by Hitachi High-Technologies Corporation).

The results are shown in Table 1.

TABLE 1 Trans- Trans- Absorb- Absorb- mittance at mittance at ance at ance at 365 405 365 405 nm [%] nm [%] nm[-] nm [-] Bismaleimide MIZ-001 19 88 — — compound (A) Photo Omnirad 819 — — 0.32 0.18 initiator (C) Omnirad 369 — — 0.48 0.04 Omnirad 907 — — 0.10 0.01 Compound (D) Cis-4- 97 98 — — containing one cyclohexene- or more 1,2- carboxy dicarboxylic groups anhydride

[Synthesis of Maleimide Compound (TMDM)]

A compound represented by the formula (19) (TMDM) was synthesized as follows.

[Synthesis of Amide Acid Compound (hereinafter, abbreviated as MA-TMDA)]

First, MA-TMDA represented by the formula (31) was synthesized by the following method.

In a 100 mL four neck flask equipped with an argon inlet, a Dienstark apparatus, a Dimroth condenser tube and a thermometer, 5.2 g (53 mmol) of maleic anhydride, 20 mL of N-methylpyrrolidone (NMP) and 20 mL of toluene were added, and stirred under a stream of argon at room temperature (25° C.) to dissolve maleic anhydride completely. To this solution, 5.0 g (19 mmol) of TMDA (manufactured by Nipponjunryo Chemicals Co., Ltd., a mixture of 5-amino-1,3,3-trimethyl-1-(4-aminophenyl)-indane and 6-amino-1,3,3-trimethyl-1-(4-aminophenyl)-indane) and 10 mL of NMP were added, and the mixture was stirred at room temperature (25° C.) for 17 hours.

A fraction of the reaction solution was collected, water and ethyl acetate were added thereto, and the mixture was shaken. Thereafter, the organic layer was taken out and dried over magnesium sulfate. The solvent was distilled off from the supernatant at 40° C. to obtain a yellow oil. The ¹H-NMR measurement was carried out, and it was verified that the yellow oil was MA-TMDA represented by the formula (31).

The signals of ¹H-NMR of MA-TMDA represented by the formula (31) are shown below. In addition, the ¹H-NMR chart is shown in FIG. 1 .

¹H-NMR (300 MHz, DMSO-d6) δ (ppm): 10.40 (m, 2H, —COOH), 7.30 (m, 7H, ArH), 6.33 (m, 4H, ═CH—), 2.11 (m, 2H, —CH₂—), 1.48 (d, 3H, —CH₃), 1.21 (d, 3H, —CH₃), 0.92 (d, 3H, —CH₃)

[Synthesis of TMDM]

To the above reaction solution, 0.67 g (3.5 mmol) of p-toluenesulfonic acid monohydrate was added, and the mixture was heated to reflux at 127° C. for 2.5 hours. After the reaction solution was cooled to room temperature (25° C.), the reaction solution after cooling was poured into a mixed solution of 50 mL of saturated aqueous sodium bicarbonate solution and 100 mL of ethyl acetate while stirring. Furthermore, 100 mL of water and 100 mL of ethyl acetate were added thereto, and the mixture was stirred and allowed to stand for 5 minutes. Thereafter, the solution was separated, and the aqueous layer was extracted three times with 50 mL of ethyl acetate. All the organic layers were combined and washed once with 100 mL of water, once with 10 mL of brine, and twice with 5 mL of brine. The organic layer was dried over magnesium sulfate, the solids were filtered off, and thereafter, the solvent was distilled off at 40° C. to obtain a yellow solid.

The obtained yellow solid was dissolved in 6.5 mL of acetone, and the acetone solution was poured into 300 mL of water. The precipitated solid was collected by filtration, washed with a small amount of isopropyl alcohol (IPA), and thereafter, dried under reduced pressure at 50° C. for 20 hours to obtain 5.71 parts by mass of yellow solid. The ¹H-NMR measurement was carried out, and it was verified that the yellow solid was the maleimide compound (TMDM) represented by the formula (19).

The signals of ¹H-NMR of TMDM are shown below. In addition, the ¹H-NMR chart is shown in FIG. 2 .

¹H-NMR (300 MHz, DMSO-d6) δ (ppm): 7.19 (m, 11H, ArH, —CH═CH—), 2.42 (m, 2H, —CH₂—), 1.66 (d, 3H, —CH₃), 1.32 (d, 3H, —CH₃), 1.00 (d, 3H, —CH₃)

Example 1

[Fabrication of Resin Composition and Resin Sheet]

168.8 parts by mass of methyl ethyl ketone (manufactured by Idemitsu Kosan Co., Ltd.) as the organic solvent was mixed with respect to 60 parts by mass of MIZ-001 (product name) as the bismaleimide compound (A), 25 parts by mass of BCPH13 (product name) manufactured by Gunei Chemical Industry Co., Ltd. as the maleimide compound (B), 15 parts by mass of TMDM as the maleimide compound (B), 5 parts by mass of bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Omnirad (registered trademark) 819 (product name) as the photo initiator (C), and 10 parts by mass of cis-4-cyclohexene-1,2-dicarboxylic anhydride (manufactured by Tokyo Kasei Kogyo Co., Ltd.) as the compound (D) containing one or more carboxy groups, and the mixture was stirred in a hot water bath of 90° C., thereby obtaining a varnish (resin composition). This varnish was added dropwise onto a PET film with a thickness of 38 μm (Unipeel (registered trademark) TR1-38 (product name) manufactured by UNITIKA LTD.), and a coating film was formed by spin coating (at 300 rpm for 10 seconds, and thereafter, at 1000 rpm for 30 seconds). The obtained coating film was dried at 90° C. for 5 minutes to obtain a resin sheet in which the PET film was used as a support and the thickness of the resin layer was 10 μm.

(Fabrication of Resin for Evaluation)

The resin surfaces of the obtained resin sheets were pasted together, and a vacuum laminator (manufactured by Nikko-Materials Co., Ltd.) was used to perform vacuum drawing (5.0 hPa or less) for 30 seconds, followed by lamination molding at a pressure of 10 kgf/cm² and a temperature of 70° C. for 30 seconds. Furthermore, by performing lamination molding at a pressure of 7 kgf/cm² and a temperature of 70° C. for 60 seconds, a resin for evaluation with supports on both surfaces was obtained.

(Fabrication of Inner Layer Circuit Substrate) After forming an inner layer circuit in a BT (bismaleimide triazine) resin laminate with a glass cloth base material, both surfaces of which are copper clad (copper foil thickness of 18 μm, thickness of 0.2 mm, CCL (registered trademark)-HL832NS (product name) manufactured by Mitsubishi Gas Chemical Company, Inc.), both surfaces were subjected to roughening treatment for copper surfaces with CZ8100 (product name) manufactured by MEC Co., Ltd., thereby obtaining an inner layer circuit substrate.

(Fabrication of Laminate for Evaluation)

The resin surface of the obtained resin sheet was disposed on the copper surface (one surface) on the inner layer circuit substrate described above, and a vacuum laminator (manufactured by Nikko-Materials Co., Ltd.) was used to perform vacuum drawing (5.0 hPa or less) for 30 seconds, followed by lamination molding at a pressure of 10 kgf/cm² and a temperature of 70° C. for 30 seconds. Furthermore, by performing lamination molding at a pressure of 10 kgf/cm² and a temperature of 70° C. for 60 seconds, a laminate for evaluation in which the inner layer circuit substrate, the resin layer and the support were laminated was obtained.

Example 2

A varnish and a resin sheet were obtained in the same manner as in Example 1 except that, as the bismaleimide compound (A), 50 parts by mass of MIZ-001 (product name) was used instead of 60 parts by mass of MIZ-001 (product name), and as the maleimide compound (B), 25 parts by mass of TMDM was used instead of 15 parts by mass of TMDM. Using the resin sheet, a resin for evaluation and a laminate for evaluation were obtained in the same manner as in Example 1.

Example 3

A varnish and a resin sheet were obtained in the same manner as in Example 1 except that, as the bismaleimide compound (A), 55 parts by mass of MIZ-001 (product name) was used instead of 60 parts by mass of MIZ-001 (product name), and as the maleimide compound (B), 20 parts by mass of TMDM was used instead of 15 parts by mass of TMDM. Using the resin sheet, a resin for evaluation and a laminate for evaluation were obtained in the same manner as in Example 1.

Example 4

A varnish and a resin sheet were obtained in the same manner as in Example 1 except that, as the bismaleimide compound (A), 65 parts by mass of MIZ-001 (product name) was used instead of 60 parts by mass of MIZ-001 (product name), and as the maleimide compound (B), 10 parts by mass of TMDM was used instead of 15 parts by mass of TMDM. Using the resin sheet, a resin for evaluation and a laminate for evaluation were obtained in the same manner as in Example 1.

Example 5

A varnish and a resin sheet were obtained in the same manner as in Example 1 except that, as the maleimide compound (B), 15 parts by mass of BMI-70 (product name) manufactured by KI Chemical Industry Co., LTD. which is represented by the formula (20) was used instead of 15 parts by mass of TMDM. Using the resin sheet, a resin for evaluation and a laminate for evaluation were obtained in the same manner as in Example 1.

Example 6

A varnish and a resin sheet were obtained in the same manner as in Example 1 except that, as the maleimide compound (B), 15 parts by mass of BMI-80 (product name) manufactured by KI Chemical Industry Co., LTD. which is represented by the formula (21) was used instead of 15 parts by mass of TMDM. Using the resin sheet, a resin for evaluation and a laminate for evaluation were obtained in the same manner as in Example 1.

Example 7

A varnish and a resin sheet were obtained in the same manner as in Example 1 except that, as the maleimide compound (B), 15 parts by mass of BMI-2300 (product name) manufactured by Daiwa Kasei Industry Co., LTD. which is represented by the formula (22) was used instead of 15 parts by mass of TMDM. Using the resin sheet, a resin for evaluation and a laminate for evaluation were obtained in the same manner as in Example 1.

Example 8

A varnish and a resin sheet were obtained in the same manner as in Example 1 except that, as the maleimide compound (B), 25 parts by mass of MIR-3000 (product name) manufactured by Nippon Kayaku Co., Ltd. which is represented by the formula (18) was used instead of 25 parts by mass of BCPH13 (product name) manufactured by Gunei Chemical Industry Co., Ltd. Using the resin sheet, a resin for evaluation and a laminate for evaluation were obtained in the same manner as in Example 1.

Example 9

A varnish and a resin sheet were obtained in the same manner as in Example 8 except that, as the maleimide compound (B), 15 parts by mass of BMI-70 (product name) manufactured by KI Chemical Industry Co., LTD. which is represented by the formula (20) was used instead of 15 parts by mass of TMDM. Using the resin sheet, a resin for evaluation and a laminate for evaluation were obtained in the same manner as in Example 1.

Example 10

A varnish and a resin sheet were obtained in the same manner as in Example 8 except that, as the maleimide compound (B), 15 parts by mass of BMI-80 (product name) manufactured by KI Chemical Industry Co., LTD. which is represented by the formula (21) was used instead of 15 parts by mass of TMDM. Using the resin sheet, a resin for evaluation and a laminate for evaluation were obtained in the same manner as in Example 1.

Example 11

A varnish and a resin sheet were obtained in the same manner as in Example 8 except that, as the maleimide compound (B), 15 parts by mass of BMI-2300 (product name) manufactured by Daiwa Kasei Industry Co., LTD. which is represented by the formula (22) was used instead of 15 parts by mass of TMDM. Using the resin sheet, a resin for evaluation and a laminate for evaluation were obtained in the same manner as in Example 1.

Example 12

A varnish and a resin sheet were obtained in the same manner as in Example 1 except that, as the photo initiator (C), 5 parts by mass of Omnirad (registered trademark) 369 (product name) was used instead of Omnirad (registered trademark) 819 (product name). Using the resin sheet, a resin for evaluation and a laminate for evaluation were obtained in the same manner as in Example 1.

Example 13

A varnish and a resin sheet were obtained in the same manner as in Example 1 except that, as the photo initiator (C), 5 parts by mass of Omnirad (registered trademark) 907 (product name) was used instead of Omnirad (registered trademark) 819 (product name). Using the resin sheet, a resin for evaluation and a laminate for evaluation were obtained in the same manner as in Example 1.

Comparative Example 1

112.5 parts by mass of methyl ethyl ketone as the organic solvent was mixed with respect to 60 parts by mass of MIZ-001 (product name) as the bismaleimide compound, 5 parts by mass of Omnirad (registered trademark) 819 (product name) as the photo initiator, and 10 parts by mass of cis-4-cyclohexene-1,2-dicarboxylic anhydride (manufactured by Tokyo Kasei Kogyo Co., Ltd.) as the compound containing one or more carboxy groups, and the mixture was stirred in a hot water bath of 90° C., thereby obtaining a varnish (resin composition). Using this varnish, a resin sheet was obtained in the same manner as in Example 1. Using this resin sheet, a resin for evaluation and a laminate for evaluation were obtained in the same manner as in Example 1.

Comparative Example 2

150 parts by mass of methyl ethyl ketone as the organic solvent was mixed with respect to 60 parts by mass of MIZ-001 (product name) as the bismaleimide compound, 25 parts by mass of BCPH13 (product name) manufactured by Gunei Chemical Industry Co., Ltd. as the maleimide compound, 5 parts by mass of Omnirad (registered trademark) 819 (product name) as the photo initiator, and 10 parts by mass of cis-4-cyclohexene-1,2-dicarboxylic anhydride (manufactured by Tokyo Kasei Kogyo Co., Ltd.) as the compound containing one or more carboxy groups, and the mixture was stirred in a hot water bath of 90° C., thereby obtaining a varnish (resin composition). Using this varnish, a resin sheet was obtained in the same manner as in Example 1. Using this resin sheet, a resin for evaluation and a laminate for evaluation were obtained in the same manner as in Example 1.

Comparative Example 3

A varnish and a resin sheet were obtained in the same manner as in Comparative Example 2 except that, as the maleimide compound, 15 parts by mass of TMDM was used instead of 25 parts by mass of BCPH13 (product name) manufactured by Gunei Chemical Industry Co., Ltd. Using the resin sheet, a resin for evaluation and a laminate for evaluation were obtained in the same manner as in Example 1.

Comparative Example 4

A varnish and a resin sheet were obtained in the same manner as in Example 1 except that, as the bismaleimide compound, 50 parts by mass of MIZ-001 (product name) was used instead of 60 parts by mass of MIZ-001 (product name), and as the maleimide compound, 25 parts by mass of IPBM (product name) manufactured by Kawaguchi Chemical Industry Co., LTD. which is represented by the formula (32) was used instead of 15 parts by mass of TMDM. Using the resin sheet, a resin for evaluation and a laminate for evaluation were obtained in the same manner as in Example 1.

Comparative Example 5

A varnish and a resin sheet were obtained in the same manner as in Example 1 except that, as the bismaleimide compound, 50 parts by mass of MIZ-001 (product name) was used instead of 60 parts by mass of MIZ-001 (product name), and as the maleimide compound, 25 parts by mass of BMI-TMH (product name) manufactured by Daiwa Kasei Industry Co., LTD. which is represented by the formula (33) was used instead of 15 parts by mass of TMDM. Using the resin sheet, a resin for evaluation and a laminate for evaluation were obtained in the same manner as in Example 1.

Comparative Example 6

A varnish and a resin sheet were obtained in the same manner as in Example 1 except that, as the bismaleimide compound, 50 parts by mass of MIZ-001 (product name) was used instead of 60 parts by mass of MIZ-001 (product name), and as the maleimide compound, 25 parts by mass of BMI-6100 (product name, in the formula (34), x is 18 and y is 18) manufactured by Designer Molecules Inc. which is represented by the formula (34) was used instead of 15 parts by mass of TMDM. Using the resin sheet, a resin for evaluation and a laminate for evaluation were obtained in the same manner as in Example 1.

[Measurement and Evaluation of Physical Property]

The varnishes (resin compositions), the resins for evaluation, and the resin sheets, which had been obtained in Examples and Comparative Examples, were measured and evaluated in accordance with the following methods. The results are shown in Tables 2 and 3 and FIG. 3 .

<Solubility>

In the obtained varnish (resin composition), the resin components remained undissolved were visually observed. The solubility was visually evaluated in accordance with the following criteria.

“AA”: when no undissolved remaining was observed in the varnish, it was evaluated as “AA”.

“CC”: when any undissolved remaining was observed in the varnish even if only slightly, it was evaluated as “CC”.

<Photocurability>

By using a photo DSC (DSC-2500 (brand name) manufactured by TA Instruments Japan Inc.) equipped with a light source (Omnicure (registered trademark) 52000 (product name) manufactured by U-VIX Corporation) that is capable of being irradiated with an active energy ray including a wavelength of 200 to 600 nm, the obtained resin for evaluation was irradiated with an active energy ray including a wavelength of 200 to 600 nm at an illuminance of 30 mW and for an exposure time of 3.5 minutes, thereby obtaining a graph of time (sec) on the horizontal axis and heat flow (mW) on the vertical axis.

A graph of time (sec) on the horizontal axis and heat flow (mW) on the vertical axis was obtained under the same conditions as described above except that a filter for a ray with a wavelength of 405 nm (h-line) was used, and an active energy ray including a wavelength of 405 nm (h-line) was used.

In each graph, the enthalpy (J/g) was defined as the peak area when a line was drawn horizontally from the endpoint of the graph. The curability was evaluated in accordance with the following criteria.

“AA”: enthalpy was 1 (J/g) or more.

“CC”: enthalpy was less than 1 (J/g).

Note that an enthalpy of 1 (J/g) or more means that the curing of the resin is sufficiently advanced by exposure at a predetermined wavelength.

<Tackiness>

For the obtained resin sheet, the tackiness was evaluated in accordance with the following criteria by measuring the height of the support being lifted up when a finger was pressed against a surface of the resin and held for 1 second, and then the finger was lifted up.

“AA”: the height of the support being lifted up was less than 1 cm from the reference plane.

“CC”: the height of the support being lifted up was 1 cm or more from the reference plane.

<Alkaline Developability>

Using a light source capable of applying an active energy ray including a wavelength of 405 nm (h-line) (MA-20 (product name) manufactured by MIKASA CO., LTD), the obtained laminate for evaluation was irradiated from above the support at an irradiation amount of 200 mJ/cm² to expose a half of the resin layer while the other half is unexposed. Thereafter, the support (PET film) was peeled, and the laminate was shaken in aqueous 2.38% TMAH (tetramethylammonium hydroxide) solution (developing solution, manufactured by Tokuyama Corporation) for 90 seconds. At this time, developability was verified upon shaking for 60 seconds, and when there was undissolved remaining, shaking was carried out for further 30 seconds. The alkaline developability was visually evaluated in accordance with the following criteria.

“AA”: the exposed portion is not dissolved, and the unexposed portion is dissolved by shaking for 60 seconds.

“CC”: either the exposed portion or the unexposed portion is not dissolved.

FIG. 3 shows photographs after alkaline development performed with the use of the resin sheets which were obtained in Example 1 and Comparative Example 6.

TABLE 2 Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 ple 7 Bismaleimide MIZ-001 60 50 55 65 60 60 60 compound (A) Maleimide BCPH13 25 25 25 25 25 25 25 compound (B) MIR-3000 TMDM 15 25 20 10 BMI70 15 BMI-80 15 BMI-2300 15 IPBM BMI-TMH BMI-6100 Photo Omnirad 819 5 5 5 5 5 5 5 initiator (C) Omnirad 369 Omnirad 907 Compound (D) cis-4-Cyclohexene- 10 10 10 10 10 10 10 containing one 1,2-dicarboxylic or more anhydride carboxy groups Evaluation Solubility AA AA AA AA AA AA AA results Photocurability AA AA AA AA AA AA AA (405 nm) Photocurability AA AA AA AA AA AA AA (200-600 nm) Tackiness AA AA AA AA AA AA AA Alkaline AA AA AA AA AA AA AA developability Exam- Exam- Exam- Exam- Exam- Exam- ple 8 ple 9 ple 10 ple 11 ple 12 ple 13 Bismaleimide MIZ-001 60 60 60 60 60 60 compound (A) Maleimide BCPH13 25 25 compound (B) MIR-3000 25 25 25 25 TMDM 15 15 15 BMI70 15 BMI-80 15 BMI-2300 15 IPBM BMI-TMH BMI-6100 Photo Omnirad 819 5 5 5 5 initiator (C) Omnirad 369 5 Omnirad 907 5 Compound (D) cis-4-Cyclohexene- 10 10 10 10 10 10 containing one 1,2-dicarboxylic or more anhydride carboxy groups Evaluation Solubility AA AA AA AA AA AA results Photocurability AA AA AA AA AA AA (405 nm) Photocurability AA AA AA AA AA AA (200-600 nm) Tackiness AA AA AA AA AA AA Alkaline AA AA AA AA AA AA developability

TABLE 3 Comparative Comparative Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Bismaleimide compound (A) MIZ-001 60 60 60 50 50 50 Maleimide compound (B) BCPH13 25 25 25 25 MIR-3000 TMDM 15 BMI70 BMI-80 BMI-2300 IPBM 25 BMI-TMH 25 BMI-6100 25 Photo initiator (C) Omnirad 819 5 5 5 5 5 5 Omnirad 369 Omnirad 907 Compound (D) containing one cis-4-Cyclohexene-1,2- 10 10 10 10 10 10 or more carboxy groups dicarboxylic anhydride Evaluation results Solubility AA AA CC CC CC AA Photocurability (405 nm) AA AA AA AA AA AA Photocurability (200-600 nm) AA AA AA AA AA AA Tackiness CC CC AA AA AA AA Alkaline developability AA AA AA AA AA CC

Tables 2 and 3 reveal that according to the present embodiment, a varnish having good solubility can be obtained. In addition, a resin sheet having satisfactorily suppressed tackiness can be obtained. The resin composition of the present embodiment is properly light-sensitive and can be photocured when exposed with any of an active energy ray including a wavelength of 405 nm (h-line) and an active energy ray including a wavelength of 200 to 600 nm. Moreover, in the unexposed portion, the resin composition has excellent alkaline-developability.

The present application is based on Japanese Patent Application No. 2019-223947 filed on Dec. 11, 2019, the contents of which are incorporated herein by reference.

INDUSTRIAL APPLICABILITY

The resin composition of the present embodiment has good solubility and photocurability, and therefore industrially useful, and can be used for applications including, a photosensitive film, a photosensitive film with a support, a prepreg, a resin sheet, a circuit substrate (applications for a laminate, applications for a multilayer printed wiring board, and the like), a solder resist, an underfill material, a die bonding material, a semiconductor sealing material, a hole filling resin, and a component embedding resin. 

The invention claimed is:
 1. A resin composition comprising: a bismaleimide compound (A) comprising a constituent unit represented by the following formula (1), and maleimide groups at both ends of the molecular chain, at least two maleimide compounds (B) selected from the group consisting of a compound represented by the following formula (2), a compound represented by the following formula (3), a compound represented by the following formula (4), a compound represented by the following formula (5), a compound represented by the following formula (6), and a compound represented by the following formula (7), a photo initiator (C) and a compound (D) comprising one or more carboxy groups:

wherein R₁ represents a linear or branched alkylene group having 1 to 16 carbon atoms, or a linear or branched alkenylene group having 2 to 16 carbon atoms; R₂ represents a linear or branched alkylene group having 1 to 16 carbon atoms, or a linear or branched alkenylene group having 2 to 16 carbon atoms; each R₃ independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 16 carbon atoms, or a linear or branched alkenyl group having 2 to 16 carbon atoms; and each n₁ independently represents an integer of 1 to 10,

wherein each of R₄, R₅, and R₆ independently represents a hydrogen atom, a hydroxyl group, or a linear or branched alkyl group having 1 to 6 carbon atoms and optionally having a substituent; and n₂ represents an integer of 1 to 10,

wherein each R₇ independently represents a hydrogen atom or a methyl group; and n₃ represents an integer of 1 to 10,

wherein each of R₈, R₉, and R₁₀ independently represents a hydrogen atom, or a linear or branched alkyl group having 1 to 8 carbon atoms and optionally having a substituent,

wherein each R₁₁ independently represents a hydrogen atom, a methyl group, or an ethyl group; and each R₁₂ independently represents a hydrogen atom or a methyl group,

wherein each R₁₃ independently represents a hydrogen atom, a methyl group, or an ethyl group, and

wherein each R₁₄ independently represents a hydrogen atom or a methyl group; and n₄ represents an integer of 1 to
 10. 2. The resin composition according to claim 1, wherein the photo initiator (C) comprises a compound represented by the following formula (8):

wherein each R₁₅ independently represents a group represented by the following formula (9) or a phenyl group; and

wherein -* represents a bonding hand, and each R₁₆ independently represents a hydrogen atom or a methyl group.
 3. The resin composition according to claim 1, wherein the compound (D) comprising one or more carboxy groups is at least one selected from the group consisting of a compound represented by the following formula (10), a compound represented by the following formula (11), a compound represented by the following formula (12), and a compound represented by the following formula (13):

wherein each R₁₇ independently represents a hydrogen atom, a hydroxyl group, a carboxy group, an amino group or an aminomethyl group; each k independently represents an integer of 1 to 5; and when two or more carboxy groups are present, the carboxy groups are optionally linked together to form an acid anhydride,

wherein each R₁₈ independently represents a hydrogen atom, a hydroxyl group, a carboxy group, a carboxymethyl group, an amino group or an aminomethyl group; each 1 independently represents an integer of 1 to 9; when two or more carboxy groups are present, the carboxy groups are optionally linked together to form an acid anhydride; and when a carboxymethyl group is present, the carboxymethyl group and the carboxy group are optionally linked together to form an acid anhydride,

wherein each R₁₉ independently represents a hydrogen atom, a hydroxyl group, a carboxy group, a carboxymethyl group, an amino group or an aminomethyl group; each m independently represents an integer of 1 to 9; when two or more carboxy groups are present, the carboxy groups are optionally linked together to form an acid anhydride; and when a carboxymethyl group is present, the carboxymethyl group and the carboxy group are optionally linked together to form an acid anhydride, and

wherein each R₂₀ independently represents a hydrogen atom, a hydroxyl group, a carboxy group, a carboxymethyl group, an amino group or an aminomethyl group; each o independently represents an integer of 1 to 5; when one or more carboxy groups are present, the carboxymethyl group and the carboxy group are optionally linked together to form an acid anhydride; when two or more carboxy groups are present, the carboxy groups are optionally linked together to form an acid anhydride; and when two or more carboxymethyl groups are present, the carboxymethyl groups are optionally linked together to form an acid anhydride.
 4. A resin sheet comprising: a support; and a resin layer disposed on one surface or both surfaces of the support, wherein the resin layer comprises the resin composition according to claim
 1. 5. The resin sheet according to claim 4, wherein the resin layer has a thickness of 1 to 50 μm.
 6. A multilayer printed wiring board comprising: an insulation layer; and a conductor layer formed on one surface or both surfaces of the insulation layer, wherein the conductor layer comprises the resin composition according to claim
 1. 7. A semiconductor device comprising the resin composition according to claim
 1. 